I think if you have a record over many years of short visits there isn't a problem ...I've never been asked at immigration for proof of onward flight /trip . Often take about 4-6 short trips each year . However ,some airlines now ask for proof of onward trip .....so I don't fly with them, though it seems pretty arbitrary often depends on the check in clerk
yep ...depends on the airline ...and even the check in person whether they ask or not .....immigration seldom if ever ask for proof of onward journey unless they have a suspicion you might overstay or not have enough funds for trip