Tightening a cog without a chain whip

you could of course stop properly:)
Must admit never to bothering with chain whip. Hand tight then ride it and mine are always a complete bugger to remove. Never had one undo let alone with a lock ring

If you don't skid stop then you probably won't. If you do skid stop then if will come undone very easily if you don't have a lockring.
Guess that is what you mean by stopping properly, i.e. using a brake.