I realize you're saying the streak occurs when you overlap a tiny bit on the previous row (I think I interpreted that correctly)...but I think...
?You may be pushing your fingers just a little too hard on the terry sponge, and more product is coming out that you want. When "gergmon" came up to do his in my garage, he kept having that problem, his fingers were pushing too hard on the sponge thing and it made 4 streaks horizontally...so I mentioned to keep your fingers vertical when going horizontally with the applicator.
I think the term is "feathering"...I generously applied the product horizontally and completed a pass on the entire SECTION I was doing, then immediately took the sponge thing and went back over it using lighter and lighter pressure until it looked really uniform......but also DON'T go over so much that it dries it out (I made that mistake on my front driver's bumper).