I think males are biologically programed to stay in heat way longer than females, at least until the first baby is born, just that modern society has figured how to tame us by placing us in a financial rat race where it all about chasing material things, hobbies and lifestyles or the next big career rather than the next potential partner.
As a kid I never really understood the point Fight Club was trying to make but as an adult, I do now.
About eight weeks later, I took him for a walk along the same canal and let him off. Rounded a corner where he'd got a bit ahead, and he was just gone, disappeared without a trace. I started off as quickly as I could down the canal, passing various people who (as if it were some kind of joke) said things like "oh yes, going very fast that way". Eventually, got him back because a cyclist had the common sense to apprehend him and wait for me - "my dog does this all the time." This was after almost a mile, so the dog hadn't been hanging around.
Beardies have a reputation for going AWOL, but on this occasion I can only presume he had some memory of that fine young spaniel he'd pursued previously, and decided to rejoin the chase. I haven't been back there since. Have considered getting him neutered but we basically like him as he is and have learned to be super-careful at any time. Helps to be warned if someone has a bitch who is likely to be especially interesting at a given time, most owners are good about it but a few just don't seem to understand.
I assumed "off leash" because if he can run off even when on a leash, then it's worse than I imagined.