Before you over-think sets and reps, first make sure your execution is on point. This is especially true for those muscles you think of as "stubborn," like your calves.
Apply this execution trick to your calf exercises and you'll see breakthrough results:
Simply focus on pushing through your big toe. That's it. Simple, yes, but are you doing it?
Here's one exercise to try it with:
Pushing through your big toe further activates your gastrocnemius. Sure, basic anatomy would tell you that your calves don't insert anywhere near your big toe, but consider leverage.
Look at what happens when you calf raise without thinking about your big toe. Your foot will tend to roll a little towards the outside. While the foot might still be straight and you'll see no roll in the ankle, what part of your foot is the pressure actually going through? Usually it's more towards the outside.
That's because your body doesn't give a damn that you're trying to build your calves. Instead, it just wants to take the path of least resistance to lift the weight up.
Now, try that calf raise again, but this time pushing through your big toe. Your foot should be in the exact same position with the balls of the feet pressing down into the floor. But your focus should be on driving your big toe down as hard as you can while you raise up. Now do you feel the tension you've been missing out on?
Your big toe is longest and furthest away (unless you have mutant feet). Pushing through your big toe actually puts you at a mechanical disadvantage since you're pressing down more with the inside of your foot. This prevents your body from taking the path of least resistance (pressure outside of your foot) and forces your calves to work harder.
Execute every single rep like this and you'll notice an almost immediate difference in your calves.
Start with basic and more supported calf raises. Do single-leg variations where you can really zone-in on that big toe. Once you've honed your execution with more support, then start integrating your newly-found big toe into more complex variations, like walking calf raises:
Alternating each step and pressing through your big toe takes focus. This is especially true if your big toe hasn't gotten much attention previously. Doing calf exercises barefoot or wearing some minimalist shoes wouldn't be a bad idea either.