Largely backing RAB on this. they can keep their legs crossed a long time but it IS rather dependant on what is going on inside the hive and the character of the winter food.
If they are raising brood they will be using the pollen stores too and thus will generate more waste, so the period of confinement they can take is lessened.
Same for high protein or high complex sugar stores.......so heather honey fills the gut faster than plain old blossom honey and the cleanest of all is syrup.......the higher the protein the more the gut needs voiding. Honeydew contains some complex sugars indigestible to bees so this is probably the least suitable of all stores as frequent voiding is needed. Not a problem in most areas...............and even with heather stores its only the very longest spells of weather so cold bee flight is impossible that give rise to any issues.
Simple answer of course, as once you introduce other varaibles like too many old bees or the presence of Nosema apis all bets are off. If voiding starts inside the hive the end can come very fast.
Assuming Finman is raping the dividends of the cold climate in very low metabolic rates and clean residue free stores. (NOT pesticide residues, residues after digestion. You get paranoid on this section.)