AbigailII: In theory, it could be unlimited number of passes.
There could be a time when both players are sent to the bar, and both have 2 piece "blocks" in their home area - and if the the players keep rolling the same dice and neither could get out unless they rolled a certain amount - then it could in theory be unlimited if they never roll that dice number they need.
I'm trying to imagine a similar situation in Hyper, but can't imagine it with only 3 pieces per side in play., so I would guess there could be a limit of times in a row.... but for most others, I would think it could be unlimited.