Most players shouldn't mess with parlays at all. Parlay for a reason like a relation between 2 events or to get the 7-1 on a 3 teamer. One could get +100 on a single using 3 teamers at BOS, but likely piss them off good.
I'd prefer -104 on 3 bets to a 6-1, 3- teamer.
You don't often find the best line on something like 3 baseball sides, all at the same book, so you lose value parlaying them and gain no correlation.
You can do a Dub style parlay, but you give up a little on each line, that's probably what inspired this thread. If you do that bases is the best thing to do it with. NBA/ NFL pointspread parlays over 3 teams are awful.