Mine has been in his tank with the basking area for a good 5ish years now... he'll still freak out if I surprise him while he's basking. I've started making a little bit of noise when I walk into the room now, so he knows I'm coming and don't startle him. He'll still sometimes get a little skittish and dart into the water, but very rarely goes berserk anymore.
From time to time he'll stay up there while I'm in the room, and look at me as if to say, "oh hell, you know what? I'm not going to jump in the water just because you're here. I'm warm and comfortable and I'm not moving."