Yeah my lifehack in that department is assuming that the seals might not be perfect anymore. Plus a brief brush with seawater splashes made my iPhone speaker sound like crap for a few days a few years ago so I've decided it's not worth the risk!
Seawater destroys everything you ever loved and cared for, no IP rating will defend against that for long.
If my phone gets dirty watered, i ensure I rinse it with fresh water; really confuses the onlooker.
I have never had a (smart)watch damaged by seawater. (I am not a sailor though, I guess keeping exposure fairly short matters.)