Preparing for a triathlon involves a ton of planning and setup. I prefer get it over with as soon as possible, so as to lighten the number of things on my mind as early as I can. The longer I have to keep lists of things to do and stuff to pack in different bags, the more I forget something.
This is why I set up as much stuff at T1 as possible, as early as I can. In some races there are rules as to what you can or cannot leave overnight in T1, but in others there aren’t. I recall in the Cebu, Philippines 70.3 I did in 2016, almost nobody left anything other than their bikes, helmets, and maybe bike shoes in T1 overnight.
But I left it all, except my nutrition (don’t want to leave that out in the hot sun and overnight) and my Garmin (don’t want it stolen). So I left everything else there. This included my bib, socks, run shoes, run hat, sunglasses, sunscreen, extra water, and floor pump.
These became items I didn’t have to worry about the next morning, and a little load was lifted off my mind.