It seems deliberately confusing to me since there is no fundamental difference between voting now and voting on the day of the deadline, but the way it’s discussed and referred to seems to imply that the correct day to vote would be waiting until the last minute instead of voting just getting it out of the way weeks ahead of time.
Early voting in the US as we know it today, meaning going to a polling place to cast your vote in-person prior to election day, started in Texas in 1987 and spread to other states from there. Every state has its own specific rules regarding how long the early voting period lasts, and other aspects like how long polling places are open each day may even be left up to local governments.
Where I’m at in Texas, we have some early voting locations that stay open until 10pm, even on weekends. I’ve never had to wait more than 20 minutes to vote (and usually less) since I started voting in the 2000 election. We have 12 days to vote before election day, and even a website with real-time updates on wait times at each polling place across the county.
The drawback is there are fewer voting sites open during early voting, so people with transportation barriers will have to expend effort to get there, but you can do so on whatever day works for your schedule. On election day itself, way more polling sites are open, so there’s likely to be a site within walking distance or a short drive in denser areas, but lines are much longer than during the early voting period, and many people have to work because it’s a Tuesday and not a holiday
Also, Mississippi, Alabama, and New Hampshire have no early voting and pretty much require everyone in the entire state to vote on election day.