Oh I have used the shit outa flex seal, and generally had good luck with it.
We had a spot in our shower where a hiddlen leak rotted out the floor, then the fiberglass pan cracked from the flex, making a small leake a yuuuge one.
I slapped some flex tape on that, and it held fine for 18 months until I gutted the bathroom.
We use it in the lab to seal 3d printed casings that are used to mold gelatenous materials. Works great as a sealant and a release agent.
