Like others have said, I would strongly recommend focusing on just 1 character at a time. That will eliminate the need to switch hotbars constantly, as you can usually get by with 1 hotbar per character per AT.
You don't need to worry about trying to maximize the efficiency of each in-game day. There are not currently any mechanics that penalize you for passing too much time, at least not that I am aware of. You will spend less time progressing through each AT if you are in a mindset of trying to maximize your efficiency in terms of reducing the number of mouse clicks and scene transitions you need per interest exp gain for your target.
In many cases it makes more sense to skip time repeatedly until the times of day you need to do something to either farm topics or raise the interest exp for the character you are targeting, rather than trying to find something else you can do during those times you don't have anything productive to do for the character you are focusing on.
Everyone has their own approach. None of them are wrong. Just a matter of preference.
With that said... I do it very differently.
At the start of a fresh run, I mostly ignore people and focus heavily on improving a few of Nathan's key skills.
Video Games, Trivia, Charisma, and to a lesser extent, Fitness.
During this time I also keep all rooms of the house very clean (it helps build relationship points, which you need to beg money from other folks in the house)
Then I start juggling everyone at once, advancing them pretty evenly. Because there's a fair amount of cross-connects in topics. Becky gives topics you can use with Dick, Gina gives topics you can use with Charlie, that sort of thing.
If you focus on one at a time and advance them too far ahead, their topics change and are no longer useful with other folks.
After that, it's a matter of planning each day when Nat wakes up.
Decide which skills I want to work, which people I'm going to talk to that day (I know there schedules fairly well by that point).
Load up the hotbar for the first part of the day, then go about my schedule.
There's usually a 'reload' or 2 each day, but it's not a constant thing.
Admittedly, there's a fair amount of 'puzzling out' the schedule. But I'm the sort that enjoys that kind of challenge.
And there's rarely any 'killing time' because I don't have anything useful for Nat to do.
