Maybe I'm an outlier, but I always use a Ziplock sandwich bag and put my phone in the center pocket because I'm soaked from sweating on my rides. I have a waterproof phone. It's not the dampness that's an issue. Sweat can be pretty corrosive over time. Phone is too expensive compared to sandwich bags to risk going naked. It's also a larger phone and I found that Ziplock makes an XL sandwich bag that is large enough. The bags last about a month before they split. I ride about 1,000 miles a month. One a month seems a reasonable use of the earth's resources.
I take the phone for safety purposes including tracking by family, but also so my wife can text me to return home when she's ready to go for her part of the day's ride.