I occasionally make PCBs, as a hobby, and I would love to find a manufacturer with a next-day delivery guarantee to the US (California) for simple 2-layer PCBs. I would pay $50 just for shipping for that service, even for just 2-3 small PCBs that fit in an envelope. But to my knowledge this isn't possible. I hate designing a project, and having to wait a whole week to get my PCB. This truly hampers my creative flow... sigh
JLCPCB started making the board in less than a day, was done in two days, and mailed it to me in 3 more days (DHL delivered it a day earlier than expected). They had it in the mail to me before oshpark even sent my design to the fab (which then took a week to make the part). And oshpark was much more expensive (5X for 3 simple 2-layer boards).
I could see getting into a week-cycle (design board over weekend, send to jlcpcb sunday night, get results friday for testing), and then just read Hacker News in the down time.
As for next day, you can pay to get anything like that. Years ago I worked for a large company that had an in house PCB fab because it was cheaper than subcontracting out prototypes and production builds to third parties. They were quoting 500-800 GBP a board and much much more for Rogers for the same week production. We are truly in magical times now for how cheap this stuff has got.
But it looks like even now at best you can etch two sided boards at home.