Listen. Writing is one thing. Marketing is another thing. Taxes are yet a whole other thing. All of these things happen in different parts of our brains. I adhere to the Ghost Busters school of thought: Don't cross the streams. Trying to get those different modes of thinking to work together is a recipe for madness.
This brings us to my theme sooner than I usually get us to a theme of any kind: Separation of duties.
Functionally this means that when I'm writing, I'm writing. It's all I do. Not because that's the best way, only way, or preferred way to do anything - it's because that's how my brain works. Other folks can write for an hour or so then switch it off and go do another thing. I need more commitment than that. I seem to work best in four hour blocks. (Which, admittedly, are in crushingly short supply at the moment.) When I've done writing for the day, however, I can switch modes and shift into another brain space to do something else like marketing or administrative work. One this is sure, though. Unless there's a really compelling business or marketing deadline, writing happens first. Everything else falls after. About every other week or so, depending on how lazy I am, I pick a day to dedicate to errands. These can be business tasks or marketing copy or mailing out books or what have you. That dedicated day is a planned writing break and pre-Covid also served as my day for going to a museum or an art gallery. It seemed to work combining an official 'catch up on all the stuff' day with something fun that was meant to refill the creative well.
If I'm in a position to need to format a book for indie release, say. I fold that into the writing schedule in my project plan. It doesn't get counted as 'business', in part, because formatting a book follows logically on the heels of editing for me. I have a background in tagging content, so book formatting makes programmatic sense to me. Mostly. But most other tasks for which I am not qualified - cover art leaps immediately to mind - I 100% advocate hiring out. I feel like there's a sliding scale for return on investment. What you can afford to pay to offload anything that's not writing pays you back in writing time. When you're a broke writer not yet pulling in $$$ on books, it's a very DIY business. So split it up and put on different hats. Write when your write. Market when you market. Be a shark, if that's your thing, when you're working business. Spend money on those things that will give you the biggest ROI - for me that's editors and covers. For someone else, the greatest ROI might come from hiring someone else to format a book because that's black magic. But eventually, the goal is to begin offloading the parts of the process you don't enjoy (and I'm sorry, but if you're imagining hiring ghost writers, maybe consider finding something else to fill your time and drain your bank account?) to vendors or an assistant.
I'll give you a rare glimpse into the author assistant interview process. Spoiler - I think she nailed this interview.