Do Wi-Fi extenders actually work, or should I just buy a mesh system?

Across the home-networking communities we read, the consensus is that single-unit extenders work well for patching one specific dead zone (a back bedroom, a garage, a patio) but tend to disappoint when used to blanket a whole house. If you have multiple dead zones or need seamless roaming between rooms, a mesh system will outperform any extender. If you have one stubborn weak spot and a router you're otherwise happy with, an extender is the cheaper fix.