I suspect it is your technique.
You can't baby a rattle can. You can't push the valve part way down or any other tricks.
Spray it on with the nozzle pushed down all the way. Start your sweeping motion off the model, fully depress the valve before you get to the model, keep it moving in a smooth motion, and never, ever stop while still laying down paint on the model. And this sounds dumb, but you gotta follow through just like golf and bowling.
If you want to lay down a thin coat to bite into the substrate which lots if not most folks do, just do the above with a faster pass. But you still need to finish it off with the aforementioned technique.
It takes a little practice, but once you get it you will not have problems anymore.
I very rarely use rattle cans anymore, but when I do I can tell you with confidence that this skill is truly like riding a bike. Once you get it down you'll not forget it.
Spray cans can be fussy about heat and humidity, too. Unless you are spraying in extreme conditions, this is not likely your problem. But if you are spraying out in the garage and it's 25 degrees outside, it could be. I'm not very well versed in proper environmental conditions for spraying, but others here are and can help if that turns out to be a factor.
Anyway, that's my best guess about your problem. I think we've all done it at one time. Hope you find something helpful in our replies here.