Middle seams vs outside strips

I just want to say I have been lurking for a while and this forum is great. I hope to meet some fellow TM'ers on the road this summer as we venture up coast of Oregon.
Now the question, we have a 2001 2124 K and it leaks like a sponge. I am attacking all vents and middle seam with eternabond and 4200. How important are those outside strip thingys? I see lots of discussion on the middle seam and vents...not much on sides. Do I need to redue those as well?

Thanks in advance.