I think you just need to make it your day job. A month is about 160 hours of work time. I can write about 1500 words an hour, so I could write a 60,000 word novel in a quarter of that time. That would leave three times as many hours to do everything else once the first draft is complete… farm out some of the editing, the formatting, and the cover design, and there’s plenty of time in a month to write and release a book if you don’t need lots of research or world building (as per Richard’s comment about writing in a series).
Lionel Fanthorpe used to write a (mostly bad) novel every weekend, based on a cover and title the publisher sent him, and did that for a few years. Michael Moorcock wrote some of his most famous books in a week.