Is it not just easier to swallow rather than holding it in your mouth you scramble round for a tissue that you forgot to prepare or that has moved away.
No it is not, at least for those of us who find even the thought of it makes them retch. I don't do OWO, but as I've posted upthread I could no more swallow semen than I could fly around the room, and whilst I've never had to 'scramble' for a tissue, it wouldn't make any difference if I did.
If I had a gun to my head and my options were that or swallow pee, you can count me in for the pee