Making slots for screws — rather than simply drilling around pilot holes — is sometimes essential to allow for wood movement or for adjustability. But making those slots can be really putzy.
Did you know you can get a router bit to cut those slots? Two, in fact: one to make a slot with a countersink for a flathead screw, another for a counterbored slot for a roundhead screw. Both are proportioned for #8 screws.
Use the bit in a plunge router (or in a table-mounted router) to cut a slot in one quick operation.