If you've ever been stuck in a rut before when trying to learn something new, it could be that the technique is slightly out of your reach right now. It could also be that you're not progressing further because your mind is tired of the same thing and when frustration enters the equation then whatever you're trying to add to your reportoire becomes even harder to do.
Now is the time to take a break. I'm a fan of frequent small breaks regardless even if it's just enough time to grab a cup of coffee before you get back to it, but it's been shown that when you're struggling a quick breather will often help. Your brain is learning all the time and I mean _all_ the time. That means that when you're repeatedly failing, time after time, it is also possible to start learning the mistakes you're making and end up unwittingly adding them to your motor memory. Now you're not going to succeed straight away every time you try something new but maybe paying attention to when you are continually screwing up your cuts would be a good idea. If you notice this happening, go easy on yourself for a few minutes, grab a drink, get a kit-kat, whatever takes your focus from the cutting stand and take a breather. Those few minutes could be trimming hours off your total learning time on a set of cuts.
The other pointer I will add is something that I've learned myself about multi skill training. It's akin to taking a break but it's not quite the same. If you're busy learning for example, your double cuts and you're making progress at whatever rate you're managing, consider swapping to something else. I don't mean go bake some bread (unless you want to of course) I mean an associated skill. Something in the same vein but different. e.g. double cuts to slicing milk bottles. Static single bottles to dry cutting. nukitsuke to shiburi. Anything related but different. This gives your brain a breather and it allows what you've been trying to do, to sink in.
So basically, anything that gives your brain a breather for a short period of time will actually improve your learning curve. It's a bad idea anyway to keep hammering at something for hours and hours until you end up hating it. Theres a lot out there to learn so use your time more intelligently and you'll arrive at your goals more expediently ;)