In terms of jigs, you dont have to spend out.... this was made with an offcut of mdf ( one side was a manufactured edge ) and a couple of bits of pine to locate it for clamping to the doors / linings.
I put a couple of screw holes where the stops are going to cover them. 3mm packer on top to space down for the closing gap and when you put it on the door, you line the mdf up with the door top.
I drill out latches and cut the perimeter of the plates with a chisel and use a palm router to remove the majority of the wood, just finish the edges with a chisel where necessary
I dont do that many doors per year, so never bought a jig
Edit to add: i use a top mounted bearing bit, so you cut the hinge ( leaf ) sizes exactly where you want them to finished size. If you are switched on, you'll use the 18mm mdf to quickly place your chisel against to knock out the corners fast and accurately before removing the jig