If you want to get good as quickly as possible, there's no point in wasting time trying to perfect lower difficulties. Move up to Hard when you can, and don't be afraid to at least mess around with Lunatic before you've even done Hard 1ccs. Of course, if you can't dodge anything on Lunatic, it's pointless, but if you can at least dodge the occasional spellcard, continuespamming a Lunatic (probably one of the earlier ones: EoSD/PCB/IN, rather than the ragefest-waiting-to-happen of continuespamming MoF/SA/UFO) is a great way to warm up your eyes for a Hard run (everything on Hard looks a lot easier when you've been staring at Lunatic danmaku), and over time will train your eyes and your reflexes quickly. Lunatic is a beast of its own, and while mastery of lower difficulties gives you knowledge and a bit of initial skill training, nothing really prepares you for Lunatic better than actually playing Lunatic.
Of course, this is all in the name of "going pro." If higher difficulties aren't fun, then don't play them. For some (like me), powerrushing to the highest level is their concept of fun. For others, that won't be the case. Do what's fun for you.