Oil circulating in an engine is much like water in a river - sediment drops out when the flow slows down so, in theory, contaminants in the oil should drop out in the oil tank. The other place, as we know, is the sludge trap (which acts as a centrifuge). What worries me about using detergent oils in old engines is that they're designed to keep contaminants in suspension so they can be removed by the oil filter. With no filter fitted, the muck keeps circulating without dropping out, acting like a grinding paste between oil changes. Presumably the centrifuge will still perform (I recall a certain make of car, Fiat I believe, which used a centrifuge on the crank as its sole filter) so that should remove some of the contaminants. That said, I'd rather clean out the tank now and then rather than make regular visits to the 'sludge trap'.
Perhaps someone with a bare crankcase on the bench could advise of the feasibility of making access to the crank through the timing side, to enable the sludge trap to be serviced in situ? Assuming, of course, no-one has gone overboard staking the plug. Frankly, I don't see the need for that.