Learning from the lessons of the Occupy movement of 2014, they traded the strategy of prolonged mass sit-ins for spontaneous road blockades and circling of buildings – a “formless” protest in Lee’s words – to sustain their momentum and secure the continued goodwill of the public.

A pair of 24-year-old friends, who gave their names only as Agnes and Maggie, joined the protest at 11am and moved up and down between government offices near Harcourt Road and police headquarters the entire day.

At first, the duo did worry whether the protest would be directionless without leaders to instruct them, compared with when they took part in Occupy and students stayed on the streets for 79 days.

But as they watched how the protesters moved about, they decided “dividing and conquering” was “smarter” than just staying at Admiralty like they did during Occupy.

“I feel this way is more sustainable, especially since I feel like we’re going to be in this for the long haul,” university student Agnes said.

Maggie, a merchandiser, added: “As we also have different demands, I feel it’s more flexible and more efficient if different groups can move around so we can fulfil them at the same time.”

Student leaders had warned of the Friday showdown after the government failed to respond to their demands by the end of their Thursday deadline.

These demands included asking for a complete withdrawal of the unpopular bill, which would have allowed the transfer of fugitives to mainland China and other jurisdictions.

The government had already suspended the legislation but the students were unimpressed, declaring they did not trust the authorities not to act later.

As they started out, the protest groups knew they were relying on social media and word of mouth to gather a crowd. They knew they could only escalate their actions when they had strength in numbers.

Hence, in a poster circulated on Telegram and Facebook hours ahead of the showdown, protesters were advised to “reserve their energy” if the crowd was thin but to “play it fully” once more than 30,000 people had showed up.

Their actions stuck to this script. In the early morning, the protesters – mostly tertiary students and dressed in black – streamed in steadily near the Legislative Council complex and sat down to enjoy their breakfast, mostly takeaways from fast food chains nearby.

They ate, chatted and kept a watchful eye, at their phones and the activity around them. It was only at 11am, and almost as if without warning, they rose all at once and a wave of black soon blanketed a section of Harcourt Road – the thoroughfare in Admiralty that had been ground zero of the Occupy movement.

As they occupied the road, there appeared to be no discernible police presence, a stark contrast to the face-off on June 12 when the force then wielded shields and batons.

As the nearby government headquarters were shut after the protesters issued the warning the previous day, the crowd then rumbled on towards police headquarters in Wan Chai. Their mission: to vent their anger over the violence they accused police of displaying during the clashes of June 12.

This time, the decision to move to police headquarters was announced by a familiar figure, Joshua Wong Chi-fung, the Occupy student leader who was fresh out of prison on Monday for his role in the civil disobedience movement five years ago.

As it happened: How bill protesters continued siege of police HQ

This time, however, Wong insisted he was only playing an “assistant’s role” in the movement, disseminating information, not deciding on action.

“The protesters might not have a loudspeaker,” Wong said. “We can help them broadcast the news.”

In the humid heat just around lunchtime, some protesters who spilled over to Gloucester Road raised the possibility of picking a new target. Revenue Tower, which housed several government departments, appeared to be a handy choice nearby.

Others on the scene cheered the suggestion and they moved seamlessly as one.

Scores of protesters subsequently moved on to Immigration Tower and the Queensway Government Offices, forcing the early release of civil servants.

“If we sit on Harcourt Road every night, it will be exhausting and the forms of protests will not be as diverse as what we have now,” said Wong, as he sat alongside some 1,500 people outside police headquarters on Friday afternoon.

Council Front lawmaker Eddie Chu Hoi-dick added: “A conventional and organised protest in Hong Kong can hardly give the government any unexpected pressure.”

Edmund Cheng Wai, a Baptist University political scientist who studies political mobilisation, said the decentralised and leaderless movement was using Telegram to good effect to canvass views, vote on decisions and forge a consensus.

He noted that protesters had learned the lessons from 2014 when ordinary people grew angry with them for causing great inconvenience. This time, the protesters knew when to retreat and advance, hardly overstaying their welcome at each location.

“During Occupy, we kept doing the same thing and by the end of it lots of people were upset and frustrated that we were causing a major disturbance,” said Nicole Ho, 33, who works in the fashion industry.

Now, though, protesters could come and go as they wished and play to their own strengths, said another protester, Dawn Hong, 37, a human resources manager.

“With no leader, I feel like this instead gives people the flexibility to make their own calls to decide whether they want go to the front lines, or stay back,” Hong said.

15-hour siege of Hong Kong police headquarters ends peacefully

“As most of the protesters here are so young, I feel like it’s my role, as someone who is older, to stay out here and be on the lookout for them.”

She came after work and was still there at nearly 11pm.

But Cheng, who had been on the ground to observe the protesters over the past two weeks, warned that the new modus operandi might lead to problems when they wanted to negotiate with the government and reach an end game.

“It’s difficult to locate representatives of protesters for negotiations and set priorities of the demands for the government,” he said.

He also feared their actions might backfire as they would inevitably affect the provision of some government services. As it was, the government said “dozens of 999 requests” could not be attended to and 100 bus and minibus routes had to be diverted.

Echoing similar concerns, Ronald Tam, a 27-year-old worker of an insurance company who had taken the day off for the protest near Harcourt Road, said protesters should pick their targets carefully. They should not get in the way of people’s daily lives, he said.

“I think it’s really important to retain our good reputation right now because the government is also playing their tactics to gain some positive public opinion,” he said, referring to the softer approach adopted by police recently and the apologies offered by officials over their mishandling of the bill.

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“We shouldn’t fall into the trap, and make those who were more supportive towards us to stand with the government.”

As the one-time resident of Hong Kong Bruce Lee said, “water can flow or it can crash”. On Friday, the protesters were in full flow.

Additional reporting by Gary Cheung and Kinling Lo