I realize this will differ for different bikes, but I always find this complicated. For my electric cargo bike I like to have my phone and Garmin 1030+ and I have a pouch for water (two)

For the folding bike, I have a little handlebar bag I put my phone, etc and I have pouches.

Now I have this Surly Ogre with a Jones Bar. I already know I will want my phone. My Garmin 1030+ and my new (not used yet) Insta 360 camera. And of course, I'll want things like a place to put my gloves, sunglasses, chapstick, etc. and I'm not sure how I want to deal with water/drinks yet. How do you all set this stuff up? How many duplicate mounts do I need, Etc?