Not sure if the OP is still reading this or not, but I'll put it up for anyone that's still interested. For me, I started with 10gal batches and then had back surgery. I wanted to brew still, but I couldn't do the heavy lifting I did before. That meant a change in how I brew so I started brewing 2.5gal BIAB batches. But I do two 2.5gal batches each brew day. This takes about the same amount of time as it took me to do one 10gal because there is a lot less time heating water/chilling beer/transferring/etc. when you're only doing that with 3-4gal instead of 12-15gal.
Even without the surgery though, if my 2.5gal brewing self could go back and talk to my 10gal brewing self, I would have done this from the start. I love it because...
1. I get to brew more. It's still the same number of brew DAYS...but I double the number of brew SESSIONS meaning I improve 2x as fast.
2. If one beer is less than stellar, I can dump it and still have another beer to drink. I've dumped more beers as a 2.5gal batch brewer than I ever did as a 10gal brewer.
3. More variety. This is awesome. Yeah...there's less of each beer with only 2.5gal of each beer but I've can have 4-6 different beers on tap at any given time. Great beer is great...but you get tired of even the best beers when it's the only thing to choose from.
4. There are options for experimenting. My system allows me to make pretty repeatable batches so I can literally do two identical batches changing only a variable or two. I've done Pilsners with Brew Tan B and without, tested different types of caramel malts & amounts, water profiles, types of yeast, hops, etc.
5. "Less" cleaning. I clean my equipment one time but I've got two beers.
There are downsides to this method. Don't get me wrong. Rather than cleaning one keg, I clean two. Rather than transferring one beer, I'm transferring two. Rather than making one yeast starter (depending on what I'm brewing) I might be making two. I'm weighing out two grain bills, hop additions, water additions, etc. You get the picture. But to me, these tradeoffs are worth it.
My system is a BIAB brewery that uses two Blichmann 7.5gal pots & two Blichmann burners, a single stainless BIAB basket from ArborFab, a Blichmann Tower of Power stand & a single gas control module and RipTide pump. It's all on a stainless prep table that makes setup pretty easy. I just recently added the second pot & burner. So instead of back-to-back batches, now I can do staggered batches. This shaved about 2 hours off my brew day. Essentially...
Prep Batch 1
Mash Batch 1 & Prep Batch 2
Boil Batch 1 & Mash Batch 2
Boi Batch 2 & Clean Up Batch 1
Clean Up Batch 2
I'll close with an article I read a day or two after finding this thread. Good info:
https://smallspacebrewer.wordpress.com/2018/07/04/small-batch-brewing-and-brewing-in-small-spaces/