The more things you put on your plate, the less likely you eat all them. We tend to overestimate ourselves in many things. It is not bad but it can be frustrating if it happens often. You plan a lot, you do half of it, you're unhappy about your performance. That's why prioritisation is way more important than planning or scheduling. You can dedicate the whole day on one thing and do a lot, but when you're going to do ten things a day, something will inevitably go wrong.
It is hard to build new habits often only because we cannot prioritise our desires and needs. I want to write 500 words a day, do meditation, work-out, read a chapter of a finance book, write an essay for writing course I enrolled, learn traffic rules for driving licence exam... A shit load of stuff plus "eight" hours of work. How to the hell should I fit it into one day?
I tried scheduling. It didn't work. Seeing a full calendar makes me depressed, I already wrote that I hate to have to do something on the schedule. The only thing that seems to be working for me is to do important things first. I estimate ROI and urgency and do things that have higher estimates right in the morning. Otherwise, I won't find time to do them during the evening. Something will happen and break my plans, or I'll be too curious to do something and forget about my plans. That's how my brain works. I tried to teach it to behave in the right way, but I failed. So, using its bugs as features the only way that works for me.