The result of my many experiments is that it is super hard to count 1 2 3 4 when they only clap twice. Most of the times, within seconds, I'm 'rhythmically' counting claps. Be it 'one three one three' or whatever numbers I chose, but the number only changes with the next clap so, well, that won't work because the audience doesn't change how they clap and I'm only using two different numbers.
I'm forcing myself hard to count to 4, basically saying another number in-between claps and if it works for an extended period of time I'm so focused on keeping my own momentum and keeping the 4-count going that I don't even hear the music just the claps and I try to remember to say the other number in between 1 and 3. That also absolutely fails because I'm already checked out of whatever I'm trying to hear
I also did experiments with my friends and some of them just hear when it happens without any counting or whatever. So I tried that as well - I would listen to this with my eyes closed and mark the point when I thought the clapping has changed. I think the results were statistically as good as my internal approximation of how long 40second is until I learned to hear the exact part of music I have to hear before I say 'yeah, it's that' - but it has nothing to do with my understanding of it.