when i was having ALOT of sex ,i found that i was far less sensative and could last a long time before popping
on occasions it was bit of a chore and took some effort to pop
as already stated i think most that have frequent sex sessions encounter a similar experience
simply cutting back on sex and wanking or completely stopping for a period will get the sensitivity back
unless you have some nerve damage on your knob that has permanently desensitized it to an extent
the various potions , snake oils and home remedies out there claiming to return some sensitivity is a mine field
some have validity others complete BS
a bit of research and trial and error to see what works for the individual is in order
as sadly very little evidence is available on what truly works for the application at hand