rhm

Soaking a saddle with water softens the leather temporarily; so riding while it's soaking wet is not a good idea, because it can soften and stretch the leather permanently. I said "can" because you can sometimes reverse the process by soaking it again, reshaping it, and applying some heat to bake the correct shape back into it. This doesn't always work, and can have pretty disastrous results if done wrong.

Just letting the saddle get wet, and letting it dry again, isn't really that bad for it. But if it gets so wet that brown water is dripping off it, some soluble substance is getting leached out of the leather; and that soluble substance, whatever it is, would be better left in the leather. Proofide is supposed to seal it in; and maybe it does. But Proofide does not really replace whatever is lost.

I know I haven't answered your question; the answer is that I don't know, and you won't know until you reach the tipping point. My advice, duh, is try to put off that tipping point as long as you can.