In Beagle Pups and Bulldogs you can still select Left, Right or Both. To select "Off" in flight would require a cognitive error of even greater than average proportions, although no doubt it has been/will be done. Ordinarily you fly around with "Both" selected, aiming to keep the amount in each wing in balance. Every now and then you may have to adjust the balance by flying on L or R for a while, but quite often you can do the whole thing with "Both" selected....which is nice. Even nicer when you have one tank only and can switch the fuel on and leave it there until you've finished or are about to crash, as in a Tiger Moth.