I'm sorry but this is a horrible idea. Sure some people do it, but that doesn't make it okay to do so. RES are comfortable in water, so why do you want them to roam around on land? You are taking them away from their comfort zone, and like someone said it can (and will) cause stress. RES in nature typically do not roam around unless they want to get eaten... I believe you see them walking around when they are searching for other water sources or maybe even food, but I'm not really sure about it. Most of the pictures I've seen of RES in the wild are them basking on logs and rocks. Yes they are on land, but they aren't moving. I've even read that they sometimes stack purposely (not just because there isn't enough room) just to gain height to see if there are predators.
RES may look like they are enjoying the walk, but thats because they always have a smile on their face no matter what. Trust me, letting RES walk around is only done by careless owners. It doesn't benefit the turtles at all so why do it? I suppose some owners like to see the turltes struggling which is why they do it, just out of fascination. I feel that the RES are only looking for water or a way to escape. (As for that story of the 70 year old women allowing her turtle to roam around freely, I believe that was a Box Turtle or some type of land turtle. Those typically always roam around freely).
So do it if you want to enjoy watching torturing your RES, otherwise provide it a nice swimming and basking area and it will be happy and stressfree.