I did my foundation course just over three years ago, and in that time I have practised almost every day, (apart from being in hospital and on holiday),, even Christmas day I was sitting on the sofa with a box of tips and my monomer and powders on my knee practising smile lines, application and product control.I can't imagine the money I must have spent on products, but I can only say how worth it it has been.
My partner once asked me why I was using white tips now and not "making" my whites, and as I've never used white tips, this was one hell of a compliment.
I still practice, though now, I wipe the product off the nail tip before it cures, (not as wastefull!), but you will find that you get a feel for the product, and you will soon know if it's going ok or not.
It is like an obsession isn't it, and when you can see yourself improoving, you know it's been worthwhile. Why don't you keep a few tips that you have done, put them away in a drawer, then in say, 2 weeks time, do another few, then get the old ones out and see just how far you've come, you really will be amazed.