From experience. But really everything electric. When I was brewing with propane my records and process were much more variable.Are you saying that from experience brewing on an eBIAB system or conjecture? It's important, because I've brewed on an eBIAB about as many batches as I have on a 3 vessel, albeit only about 10 batches on an eHERMS 3V so I admit I just may not be tuned in as much.
I have found that eBIAB vs. 3V RIMS (I have never brewed with HERMS) that there are two things that drive my length of brew day: 1) 120V vs. 240V, and 2) My recipe. Sometimes I do a single rest + mashout. Sometimes I do 3 rests + mashout. Sometimes 60 minute boils and sometimes 90 minute boils.
Probably another variable here is sparge vs. no-sparge. Maybe the assumption is eBIAB = no-sparge, and 3V = 60 minute fly sparge. But obviously that isn't the case. I batch sparge in my All-In-One eBIAB units, and a 15-30 minute fly sparge in 3V.
I have brewed in: Mash & Boil (120V eBIAB), Brau Supply (120V eBIAB), Grainfather (120V eBIAB), Braumeister (240V eBIAB), BrewEasy (240V RIMS), BrewEasy Compact (240V eBIAB), Brew-Boss (240V eBIAB), Robobrew Gen1 (120V eBIAB), BrewZilla/Robobrew Gen4 (120V eBIAB), Anvil Foundry (120V eBIAB), Wort Hog (120V eBIAB), 3V (120V RIMS), 3V (240V RIMS).