Their isn’t one way to make a flat head screwdriver. Some a chisel and some are slots. The slotted ones are better but more expensive.

Both still slip from the screw and are a pain to manually screw (slotted less so).

Pozi is the best + type screw. It’s pretty much standard for UK construction. The only time a different type is used is sometimes Phillips for plaster board or external hex and internal torx for long or large screws.