First I would like to say next month marks my first year of drumming :).
The one thing I have struggled with is doubles and grooves that have consistent doubles in them. I have tried both the heel toe and slide technique and they didn't really feel comfortable at first as all things you first start to learn. But over time I notice it's not really getting any better for me. And I've been dedicating a lot of time to them since doubles have been my weakness since I started drumming. The only way I can play doubles quickly and accurately is just muscling the whole thing out with my leg. It gets the job done only thing is it makes my leg get tired way faster.
So my question is should I continue trying to do slide or heel toe and hope that one of them eventually gets better or should I start doing some conditioning and endurance exercises with my leg and work with that?