I suppose one could always just advance the thread a tiny bit manually as the arm sweeps across the LP.
Not really. The suction keeps the thread pinned between record surface and vacuum nipple, so if you untwist the spool to generate a little slack it doesn't get pulled up into the vacuum arm until the nipple clears the edge of the record. For this to work with the Monks it must actively pull the thread through. Just giving it a little slack wouldn't work.
OTOH, I don't think it's that big a deal either. Pulling a 1/4" of thread slack to refreshen it after each pass doesn't make my list of hardships! ;-)