The time spent to learn Kanji via RtK is in my experience only a very little part of the time spent on everything else related to learning Japanese. The RtK way (and I don't do flashcards) is actually a fun diversion, and I find that I enjoy drawing the characters. And that's from a guy who can't stand writing by hand in general.. I started using a typewriter at 14. And I can't draw pictures to save my life. Unlike the previous time some years back, this time I'm using a cheap click-to-erase mechanical 'magic' drawing pad. Much better than the stack of paper I used back then.