When I'm trimming a fence or a flower bed with concrete edging, I've been trying to come close enough with my string to just barely nip the hard surface so as to conserve string and wood. But this is very slow. I'm forever having to sneak up on stray pieces of grass that remain uncut and then just when I get the distance and angle right, the trimmer feeds more line and digs down into the grass more than I'd like it to. (Yes, it's an electric auto-feed trimmer.) When you guys trim, do you just get up close and buzzsaw along and cut in one fell swoop, or do you do it like I'm doing and I just need more practice? Any suggestions would be much appreciated. Thanks.