I usually only advise people to use 1 extender. If you're needing more than 1, its better to move to an actual mesh system. there's several reasons for this. In an actual mesh system there's the router controlling it. When you're just using it with extenders and you're setting them up with the same ssid (mesh), they can end up connected to each other or causing interference. It doesn't help the stability of the system.
It can be made to work but it takes more time in testing configurations and making sure distances are correct so the extenders connect properly and don't daisy chain or connect to each other.
