My experience with RL paint is different from most on this board, but I think I know the reasons. I have summarized what I did below, but let me know if you want more details.
I did MUCH more extensive prep work than normal because my walls (lath & plaster) were in very bad condition and needed a lot of repair work. I had to sand every square inch of wall, which I know helped the paint go on better.
I was also much more careful than normal in how I applied the paint, plus I stirred it constantly (i.e. every time before I loaded my paint pad). Despite this, I still had to do two coats to get an even finish. The results were good even though I used a dark color (Putting Green).
I also noticed that both the light and dark colors of RL paint that I used took a long time to dry completely (about three to four weeks) and that the color/finish changed significantly during this time. It got lighter and the streaks that I saw at first eventually went away.
I'm happy to send you more details if you want. The RL colors look great, but in my experience, good results seem to be the result of greater-than-normal prep work. I'f you're not patient and willing to invest the extra time, you may want to consider trying another brand.