DISCIPLINE
Yes please oh sorry...thats another thread elsewhere.
Right..in this case, you need discipline to do the writing. Throughout the writing journey there will be ups and downs, but you need to work through them if you want to produce a finished manuscript. Can you rigidly stick to a daily timetable to get the manuscript finished? (I know I can't). That's just one way, but not for everyone.
But you do need some regularity. Not all day, no. That's not possible. You would get burn out. but some part of the day cleared so that you can focus on the story. In my case, it was not every day. When I was writing, I aimed for 1,000 words in each writing session. Sometimes I did more - a lot more. the most I did was 5,000 words but you know what? I had to go back over that and edit, chop and change. You cannot maintain the level of concentration needed to write coherently. Well...I can't, anyway! The 1,000 words still needed editing, btw but it was mainly where I had found a better way of telling that part of the story. Sometimes, of course I did less.
I also had days where I did none and did not feel guilty about it. No sense in beating yourself up. Also, as any writer will tell...you have blocks, the dreaded 'writer's block', where you can not string sentences together much less add to the storyline. In that case...best to completely leave it and go do something else.
Still more days were spent on the research without typing a single word.
You will find your own level of discipline, of commitment, if you are serious about producing something. There is no 'right' answer - all authors do it differently, do it their own way.