Personally I think dead reckoning is innate. At least it feels that way to me. Like knowing it's about to rain, I "sense" I should be heading that way or this, instinctively I suppose, almost as if I'm being pulled, and if practice (or lack thereof) alters the effect, I haven't noticed anything so far, and I've been using using GPS for over a decade (props to HERE btw, best app for the phone, especially beyond towers). There are the odd minor digressions, like on the Vinyard last summer when my phone was constantly routing me around Obamajams onto sketchy dirt roads etc, but I told it to. Anytime things get really weird alarms go off and I reassess.
I think it's all positive, and while I'm all for model maps and peer reviewed papers, I doubt that particular spidey sense will atrophy anymore than I'll lose the ability to eat with my hands because I've been using utensils for too long. Spatial localizing isn't just a time saver, it's survival, and thanks to fuckups by the ancients we've evolved from those that were pretty damn good at it. It's ingrained, it appears, and we got it free.