What a load of crap. There are no RULES in quilting. Hundreds of quilters make art quilts that involve thread painting which uses thread buildup as part of the design.
Going over a row of stitching does not weaken anything.
Where people get the thing about not crossing their stitching is from the stippling pattern. True stippling does not have any crossed lines. Meandering does. Most pantographs do. Most any other pattern does.
Just stop listening to the "they say" quilt police, and do your own thing. It's your quilt. Do what you wish.