PCB Panelization Impact
Panelization helps your PCB cost, and it also helps assembly if your board is small.

You have a couple of options for panelization. If your board is square or rectangular, it can be scribed with with a V-groove and broken apart to singulate it after assembly. The board will have a smooth, straight edge.

If your board has an irregular shape, it will be shaped by routing, so it will be attached to the main panel by small gaps (tabs) in the routed-out slots. After assembly, the board is singulated by cutting the tabs with shears / diagonal cutters. This leaves behind a nub. You can request the assembly house to clean this up if it's a problem.