I don’t know much about manuals, but I think I might know the answer to the OP’s question and it’s related to the comments by deadkenny and others.
I reckon you are learning to manual because, like me, you read too much and think that you need to learn to manual before you can get good, In fact that’s putting the cart before the horse.
I think that people (teachers and students) look at good riders, marvel at the way they can pick the front wheel up over stuff at will (manual, bunny hop etc) then think that they can get good by learning the skills. In fact, I reckon that the skills are a consequence of being good and not the cause.
If you learn to manual (or any other “trick”) in isolation then you’ll be able to impress your mates in the carpark, but I’m not sure it will make you a better rider. Or rather, I think you’d be better off spending the time that you spent learning that trick just riding more.
Almost from the first time you ride off-road you realise that you need to lift your front wheel to get over stuff (or to stop the front dropping on drops). At first it is tricky, but with time you find that it gets easier, then it becomes natural and you do it without thinking. Finally (not that I’ve reached this stage yet) you realize that you are keeping the wheel up for multiple obstacles.
I say this as somebody who has read everything about manuals etc, watched endless videos and been on multiple coaching courses (group and one to one). In fact it was the instructor on my last one to one course who said “just ride your bike more”.