First Post
Ok this is my first post but I will give you my opinion on the question you asked.
As someone has already mentioned the PC is a muscle and should be trained like a muscle. Unfortunately it’s harder to ‘load’ a kegel so progressive overload has to be done in another way. For example, more sets, more reps, longer reps (holds) and playing about with rest periods.
Now to answer the original question do you need to do them to ‘failure’.. I would say no!
Just like other muscles training to failure causes longer recovery periods which mean you won’t be able to train the muscle at a high intensity without adequate time off.
To quickly summarise. What I would suggest is treating it more like strength training in the gym. The goal should be to get stronger in the particular contraction pattern, so you focus should really be on getting better/more efficient at the exercise over training to complete failure.. Of course some amount of fatigue is ok but I still encourage you to focus more on performance improvement of the exercise over trying to fatigue the muscle.
After all, you want to get stronger in the PC muscle, you are not looking to have a big bulging PC muscle that’s not all that strong and no one can see anyway (maybe you are if that your thing bash on with the failure and drop sets 😜😁)
Hope this helps someone.