So we bought our place 4 years ago and I got a Husqvarna robot mower year 2 because I was sick of weekends mowing, like $1100 with the wire kit. Thing's been honestly great except one thing drove me nuts: always leaves a 3-4 inch strip along the fences and the patio edge. For 2 years I assumed I had it set up wrong. Re-laid the boundary wire twice. Asked the dealer who basically shrugged. Tried more zone overlap. Nothing changed, strip stayed. Last weekend my brother in law was over (the type who reads spec sheets for fun) and he just looks at the thing and goes "yeah that's the blade position, it sits inside the wheel line, physically cant reach the edge, all of them do it." I went outside and looked. He was right. Blade is like 2 inches inside the wheel. No way it could ever cut to the edge unless the whole deck shifts. I'd been blaming the wire for 24 months. BIL also said theres a newer gen with shifted or asymmetric blades that actually fixes it (Mammotion's LUBA Mini 2 AWD, some KS one called Goalker, etc). Wish I'd known going in. If anyone needs a sign before buying: ask if the blade is centered or offset. Centered means you string trim forever. Feel really dumb only catching this 2 years later.
EDIT: yeah Mammotion has a few models doing this now and the Goalker on KS too. older / cheaper centered-disc ones generally cant. ymmv.