I do a lot of granny squares so I know about having lots of ends to weave in! Boy can it be a mess if you trim one and then it pops loose along with a few stitches!! I always try to leave my ends at least 4 inches long. When I weave them back in, I like to go back and forth kind of overlapping the points where I do weave it in to make it more strong.
I was once told that in the "golden" days, they would actually secure ends with regular thread after they wove them in! I cannot imagine stitching over every loose end I had, I'd never finish another afghan again.
Best advice, leave the ends long enough to weave in throughout your work and if they do pop out, it won't be a big deal for someone to trim them up.
Thank you ecullworm for the awesome siggie!