After how many times play, can you remember mos ntoes

You basically dont need to look the screen, it's more like hint.you dont need pay attention to each notes but help you to know the upcoming riff

Really depends on the way the riff are built. Some are really easy to learn cause they are scales, some are just really simple with 2 or 3 chord, other are a pain cause they are compose of scales change and complex chord or weird rhythm.

 

It's also a matter of what you are used to play in general, some riff are very common in some genre which makes them easier to remember.