I owned 35 websites at one point, and I was trying to make ALL of them work as businesses. It was too much! Even in my full time agency job I was trying to balance about 5 other projects on the side on the weekends and in the evenings!
Attention and mental energy is actually a resource and it DOES run out! It’s easy to think that you can just focus on things all day long but you can’t. Your brain is like a muscle, and because I can’t really remember where I found this out, you’re going to have to take my word for it, but there have been studies done proving this!
You can prove it to yourself, actually.
Try and focus on things all day long 7 days a week, with no breaks. You’ll find that at the very best, you’re just not as effective towards the end of the days, and towards the end of the week.