I know some of you are aware, but for the rest, don't forget that DF checks each layer of clothing/armor when the target takes a hit. It only displays the layer that blocks the shot, or the last layer to fail to block, when it gives the combat report entry. If the cloak stops it, it never gets to mail or brestplate. If your sock stops the attack, that means it got through your boot/shoe first.
In my experience having tons of layers is probably more of a detriment than a benefit. It takes more time and resources and makes your dwarf sluggish if they aren't skilled armor users and if they are, then they won't need tons of armor anyway. I rather have them be able to attack earlier and more often.
I haven't done the maximum layers or used danger rooms since 31.25. I find it is generally better to just get armor coverage everywhere.
I've always used the following armor coverage and have rarely had any injuries using bronze, iron, or steel armor:
1 breastplate
1 mail shirt
1 cloak
1 greave
1 pair of trousers
1 pair of gauntlets
1 pair of mittens
1 pair of high boots
1 helm
1 hood
1 shield
Bare minimum coverage while metal industry is still new or if iron is nonexistent and I gotta buy from caravan or murder invaders:
1 mail shirt
1 cloak
1 helm
1 hood
1 high boots
1 pair of gauntlets
1 pair of mittens
1 shield
Leather gear for peasants or fast marksdwarves:
1 leather armor
1 cloak
1 leather helm
1 hood
1 pair of leather leggings
1 pair of trousers
1 pair of mittens
1 pair of leather high boots
1 leather or elven shield
Marksdwarves get a wood or bone crossbow
Peasants get copper war hammers which are pretty effective for how dirt cheap they are, especially in the new version.
I haven't allowed my dwarves socks since there used to be the 1 boot bug from awhile ago and I've never noticed anything bad happen to start using socks again.
As far as I've noticed, the difference between cloth and leather is rather small, from my anectdotal evidence of masterwork rope reed cloak deflections occurring as much as leather cloaks do.
If it won't be deflected by cloth, leather is probably not gonna stop it either. The only time I prefer leather over cloth is when I use all leather armor without gauntlets.
I also melt all armor that is not at least exceptional quality and reforge it until it is exceptional or better.