Well OTC PCT is ok sometimes depending on your cycle, but I would always have a serm on hand, a popular OTC PCT is the testosterone recovery stack (TRS) from primordial, I have never heard anything bad about it, heavy doses of AI's and whatnot can lead to delayed gyno and whatnot in some cases, so the only tried and true method is to have a serm
If you are doing something mild like Hdrol I think the TRS should be ok