Ummm, no that's not what happened. See here's where I get some of you are really poor at watching and understanding a fairly easy to follow TV show. It's really not that hard. There were at least 3 different groups of Saviors. Probably more. They could have most likely had 3-4 routes blocked at a time. And after Rick's group tried each one, they had less to block.
Actually back country roads do work that way. Especially if you know them and have been around them for quite some time. The Saviors have been around the Alexandria area for probably the entire apocalypse. Rick's group has been there for a couple months? And the Saviors have been setting up road block for quite some time too (we've seen that in the show). So logically, they know the roads really well. All they needed would be a couple spotters and they could radio (we know they have them) each other to coordinate. Not really all that difficult.
Getting everyone to the one place in the woods, ok yea that's a bit of a stretch, I'll give you that. But again, it's a TV show. You're gonna get some stuff like that in any TV show (movie).