That's totally depends on you, if you wanna do it consecutive, then go on, or not, then you can just work for total 3 hours, Like 1 hour per sitting etc. But totally on you!
Does brainstorming and just flat out having the project open count towards the time or does it only count when you are doing something?
Yea, only when doing something, Keeping the project open while thinking of ideas is allowed!
