Tether recovery aims at the ledge if you're withing a 30 degree angle (approximation) above the ledge to 75 degree angle below the ledge (another approximation) and are in a recovery position (as in, off the main platform). I should know because I used this fact to dodge attacks with Ivysaur and Olimar for the last two days, and even had people watching me going "I didn't know you could do that." There are also vids posted where I've seen this. I'm not going to meticulously track one down right now just to prove something that I've done myself only hours ago, but I'll keep my eye open for one to show you.
But before I do, and people will back me up on this TETHER RECOVERY HOMES IN AT THE LEDGE. It just only happens when you're recovering. If you're on or above the main platform already, safe and sound, it'll only go in whatever angle it was designed to (ZSS goes straight up, Olimar 45 degrees).