i shock::In my case, my fc was only dropping by i shock

i shock::In my case, my fc was only dropping by.
It was only last night, after i shocked the pool, that i had a larger fc drop during the night.
My question is if the shock level of 20ppm was so high, that as a percentage, a 4ppm drop during the night was acceptable.
What i was thinking i should do, is do the nighttime fc drop test again tonight but at normal fc level, not at shock level.
If fc holds steady tonight, then i should be ok.
Does this even make sense, or should i keep the pool at shock level until it can hold a fc level of 20 without loss overnight?