Well actually mucus is secreted continuously, but it is supposed to be so thin
that you are totally unaware of it.   If that flow were to stop, you would have
problems.

But you meant, how quickly will excessive buildup of thick mucus return.

Well, it all depends.

Unfortunately, it will return in quite a few cases.     Actually, things may
get better for a while at least, while healing takes place.  You might want to
take oral steroids for a month or two right after surgery o give things a
chance to heal.     Some doctors recommendd that, and some do not.  I did that.

Really, surgery mainly just re-opens blocked openings, removes diseased tissue,
and possibly reduces the turbinates.

You have to take other measures to prevent a gradual return back to the old
state (or to ensure a full return to normalcy).  You probably have soeme time
though.

What caused the original disease?  If it was allergies, then you need to
eliminate the allergen exposure.

In my own case, which is not necessarily typical, things were perfect for a
while after surgery (of course the oral steroids were doing a lot of that),
then I got more buildup.  Things are very much now improving again now as I
take better air quality control measures, and get better diet and rest.  

So it more gives you time to deal with it than it does solve everything once
and for all.

I am way better off having had surgery......