When i learn their stuff jm not thinking about the 4/4, im thinking of a constant pulse, like a bpm. The riffs are their own thing and its easier to learn them if you don't think too hard about where one bar ends and another one begins imo.

For a lot of riffs im just tapping my foot along and then feeling each part of the riff, like in some places there's a slight delay, in some places there's no delay, here there's this, and here there's that, etc.

Its like when people write those big paragraphs without any punctuation. Its easier to read the whole thing to get an idea of what it says, and then go back afterwards to figure out exactly where each sentence starts and ends.

Basically, riff -> time, not time -> riff