The details make a big difference. It was a mile to mile and a half walk from the rally to the Capitol building. Walking it in a crowd would take about a half hour +/-. Trump's speech started almost an hour late, so the folks who left after the speech arrived at least an hour later than the glowing ones had anticipated. If Trump suspected there were any DS shenanigans planned at the Capitol, that might be why he started his speech an hour late to disrupt their plan. Either way, accidentally or purposefully, that delay saved a lot of people a whole lot of grief.