Pros do boost Japanese/ESN rubbers.
But it doesn't mean, Pros do it, you must do it too.
In fact, it is normally the other way around.
Durability, of course it will be affected. Pro race car tires don't last an hour, while mine last months. So it is all relative to usage.
Pros do get 50 sheets coming in per time, so they can change as they please.
1 thin layer should be okay.
Little booster does make a big different for many.
I do not agree with the principle of adding too many layers. That extra top speed (say from 300km/h to 320km/h means nothing, if you can't even get to 200km/h in terms of driving skills)
Too much booster, your durability drops, often people will mess the sponge up and destroy the rubber or not enjoy it.
So if any, 1 light layer is fine
Since you receive "SOME" - lucky you.
why don't you try 1 with a light layer and 1 without, and you can share you experience here.