I have not seen this noted anywhere so far (comparisons are always with Kittinger's jump duration), but it's actually a great point. Only the longest free fall would have to be counted inbetween station boosts, so it would presumably be a lot shorter (but maybe a lot longer than 4minutes?).
Way longer than 4 minutes. Station-keeping boosts on Mir were done only a few times a year (and were usually done by attached resupply crafts).