Ok so i want to have a stronger core, lets take abs as one of the points i am working on.

What i dont understand is, say i do 5 sets of planks or variations and try to build the sets over time.

Now why do a lot of people do 15 min+ ab workouts i mean in comparison they must be doing like 15 sets of abs. Is more always better?

I approached abs like other lifts so, i did 3-5 sets, now i could understand that the exercises are much lighter and more endurance based compared to my deadlifts and that therefore i could do more sets.

But say i build up to 15 sets of some ab workout, i always fear that in order to even keep that level of strength/ endurance in my abs i will have to at least do those 15 sets every fucking time i train.

Therefore isnt it best to do some very heavy ab exercise for the normal 3-5 sets?

I am kind of doubting here, please tell me where i am wrong in my thinking out loud and apologies for the incoherent rant, but i am looking for a basic proven ab strength progression like 5/31, starting strength etc are for the big 3, thanks.