Simple, 5 ways is better than 3
J/K, but look at it this way, unless it is a "vintage" that you don't want to modify, putting in a 5-way has zero negative effect. If you don't want to use 2 & 4 don't, but having it allows you to do so and you may like it. The old guys weren't wedging the 3-ways in between terminals for no reason, many of them liked the 2 & 4 positions.
Cheers!
