No idea about delay sprays, but....
....I’m guessing they film scenes at different times then splice them together to make it look a seamless long session.
Once saw a documentary about making porn and it showed all the tricks of the trade.
Yeah there have been a few documentaries which show the reality of porn and most of the actors admit it's not necessarily the dream job everyone thinks it is.
Most of these guys are able to get wood and maintain it for ages (easier now since Viagra) but they also have to shag in all sorts of places and not necessarily with girls they fancy.
Additionally while i'd shoot my load bareback in 3 strokes they seem to be able to shag and stop ejaculation somehow by just "thinking about it" was how 1 performer put it

Often a scene which lasts 20 or 30 minutes can take hours to film which means shagging for a few minutes without cumming then stopping for a while; getting wood again and more shagging in a different position; stopping etc etc
There was one guy who did gay porn but said he was straight

And I mean he was the one shagging not receiving so he had to get hard then fuck a guy who he didn't fancy and you normally have to get quite hard for anal. Not sure how the fuck he managed that even with the help of blue pills but he certainly earned his money
As for delay sprays I did once use a delay cream to see what it was like as I do cum quickly so wanted to be able to bang away for 20 minutes.
For me it just de-sensitised my cock and meant I struggled to get hard, thankfully I didn't try it on a punt but decided to go solo as a tester
