I tend to use the no 5 as its truly known, a ‘jack’ plane. It really can be great for edge jointing small parts and its much more comfortable than a 7 (i edge joint anything up to a metre with my 5, seems to work well)
I also use it when traversing boards too, I have the mouht relatively tight for a jack but never find this to be too much of an issue – I have a 5 1/2 I have set up more as a flattening plane.
It shoots well too!
It really is the jack of all trades, and it would be the last plane I give up at gun point!
I have a moderately cambered blade in my No. 5 so use it for about anything that doesn’t require a true flat cutter.
Its the first plane I put into action on every piece of wood. Its not only great for roughing, but if its properly sharp and set its can be as delicate as any smaller plane. I purchased a truly neglected, beat up old Stanley No. 5 on ebay for $35 and it is without a doubt my favorite tool on the bench.
Amongst the other uses already listed, it’s nice for truing and flattening the top of a box or drawer. It’s longer than the #4 and won’t ride up and down in the bumps and wiggles, but is small enough to be manageable. I use it for edge jointing and shooting, too.