Here's a potential explanation: if you are using radar and can see bosses, it's easy to rush the boss immediately and kill him + any guards for XP.

Let's compare my own stats, of my first wipe: https://i.imgur.com/sMAwQRb.png

A lot of those hours are the client idling, but I'd say I've played at least 1k hours since buying the game in December.

I'm playing almost only Customs, and have been doing so for the last 2-3 months, or so. I always rush Dorms, or Fortress, or pass by New Gas, which are the locations you would usually find Reshala, and I always try to kill him if I get the chance.

And you can see that I have 101 boss kills. So, something OP is doing is making him 10 times more efficient at finding and killing bosses.