Phil Pascoe
Established Member
Never found a use for a 4 1/2 - too close to the 5 1/2, but the 5 is a big step away and very useful.
It's all a matter of choice/taste - I've never seen the need for a No.5, which is probably the commonest of all, and most people's starting point. I've got 4s to an 8 and use the 4 1/2 (a frankenplane ) most, followed by the 5 1/2.