If you buy a used sailboat for refurbishing, there are a few things you have to check in order to know which parts will need replacing. Of course check for leaks, but as well for soft spots !
Especially around chain plates, stanchions, mast tabernacle, cleats, and anything that “pierces” the deck, where water can stagnate. Take a small hard object and tap it, press it to identify any soft spots. If it’s soft, then it’s probably starting to rot from the inside, and that will be an other part to replace.

A little bit of replacing is okay, but price can stack up, as well as time spent on the project.