I work full-time plus have a casual job, so I must plan my time carefully. Depending on my work schedule or what I have to do, I organize everything accordingly. I get up early to write (6 a.m) on my days off or when I have later shifts. Other tasks like recording videos, writing blogs, and social media have to be planned around everything as well; it's not easy, but I manage to make it happen.
I write one chapter per day. I try to avoid stopping halfway through because it's hard to get back into the same headspace if I walk away and return later. Editing takes longer and is much harder to schedule because some chapters are easier to get through than others, and of course, there are many rounds of editing before I can upload my book to the publisher. Meanwhile, when I'm finishing a book, I also have to start thinking about what I want for the back cover synopsis and, of course, the front cover image. Both involve marketing as much as creativity, so there are a lot of factors to consider.
It's essentially up to me how much time I want to dedicate to my writing, and therefore, it's also up to me to make the best of the time I have each day. It's really about organizing your time in advance and being self-motivated.