My rule of thumb, which is similar to yours, is as wide as will fit in the frame, but clearly you need to have a wider guard to give clearance.
Sure, the wider the better: I should have qualified my ROT as being the minimum required.
@Scilly.Suffolk started
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My rule of thumb, which is similar to yours, is as wide as will fit in the frame, but clearly you need to have a wider guard to give clearance.