With my bikes, if left sit all winter, the wetsumpers fill their sumps after a month or so and then they leak all over the floor. They don't leak when the sump is at its normal operational oil level.
For the last few years I've drained them in the fall and pulled the plug wires, plus put a big note on the speedo " No oil"
That works.
I only have one with a valve and it's nice, no leaks, no extra draining required, just like a modern bike.
Any which way is fine with me, put a valve with interlock on, or don't put one one and drain the sump after it fills, or drain it for winter, or ride the bike often and keep it pumped out that way.
It always surprises me that the folks who have never installed or used a valve with interlock get so annoyed with those of us who do use them without problem.
Glen