It has varied. I used to keep them 1-2 years when they used to improve a lot year-to-year. The last 2 phones I've had 3 years each.

After I'm done with it, I hand my phone over to my brother, who runs it into the ground over the course of the next 3 or so years, until it's almost unusably slow. My brother does the shower thing too, but less often. Maybe 30% of the time and less steamy.

It's possible that there could be gradual, over time damage. Rust growing until it forms a short. But that's not been my experience.

Ultimately, it's up to you if you want to take the risk, but given how I treated mine, if you even did this half as often as I did, you're probably fine.

I didn't mention this above, but I sometimes also used the phone inside the shower. Clicking the next video or checking a message notification. Maybe 1 in 8 days.

I've also sometimes washed the crud off the phone under the sink, rather than my normal approach with isopropyl alcohol. The worst I'd get is a notification saying I couldn't charge for a bit, or the speaker sounding funny for half an hour or so.

You might call me crazy, but I don't like to baby my stuff. I paid for water resistance, I'm going to make use of it.