Hi there!
-This is a super, I do mean super informal (learning) process to me, so we're looking at anywhere between 2-3 builds max unless more are deemed necessary.
-In timing routes, I've found that if you're a fast reader and first time, ~2 hours, but ~3.5 hours is closer to projected gameplay time! I'd recommend focusing on the one route you're drawn too if you're interested in testing but can't dedicate much time to testing!
-And it's one client for ease and my sanity! (There's the friendship and romance split at the very beginning, and further on the game splits into the individual routes.)
Hope this helps!