Yeah, because all public lands are impeccably marked.... Seriously though, good advice in theory but I’ve hunted so many different places (both public and private) where it’s not marked at all or it’s marked clearly in spots then nothing else whatsoever. This would be where these apps would be helpful. I’d still stick with your plan, I don’t trust apps like that, I take them as just overall suggestions. For the 20-40 yards thing, I trust my eyeballs.I don't understand what the big deal about being 20, 40 + yards off? Learn how property lines are marked, especially public lands, then use field evidence. Your not surviving a line with these tools.
I do want to look at that ONX thing mentioned, there are places I hunt that I’d love to find the adjacent property owner info to request permissions. County property records I’ve tried in the past give you the name, but no contact info - if these apps do that it would be spectacular and I’ll download one immediately.