Fascinating to hear about heart risks from numbing agents. I'd never heard of such a thing... but it is good to know when recommending it.
Personally I've tried many things over the years, and what works best is orajel applied heartily around the glans, then left to sit for a few minutes, then a condom - or two if I've been in denial for quite a while. The cream lasts about 15-20 minutes, though does start to wear off after that. Finding the right balance to how much to use takes a bit of practice, and as mentioned by others here - we're all a little different. Too much for one fellow which causes him to lose the erection might not be enough for another fellow who still can have an orgasm while numbed. We are all a bit different, that's for sure.
A note about the numbing condoms, they don't work well for me. The cream pushes out from the condom and eventually touches my partner and she doesn't want to be numbed. The only work around for it is to only open the numbing condom about 2/3rds down my shaft and then put another condom over it, which gets rolled down all the way.
Using condoms with bencocaine lubricant to keep from cuming
Re: Using condoms with bencocaine lubricant to keep from cum
"Some people need to be caged before they can be free." - Anon