I frequently salvage, sometimes ninja sometimes my own stuff. If using a T1 destroyer (like the Catalyst) you’re usually better off having 6 salvagers and 2 tractor beams instead of the 4-4 eve uni recommends. If you’re salvaging your own stuff the ship you did the fighting with should have dropped a MTU at the beginning of the fight so when you come back to salvage most, if not all, of the wrecks are sitting right next to the MTU without needing to be tractored. However if you’re ninja salvaging you can’t target yellow wrecks anyway so the tractor’s don’t do you any good anyways. The reason to have 6 salvagers is because as an alpha that’s the max you can target in a T1 destroyer. The only reason I equip even the 2 tractors is because I might as well fill the slots and they do occasionally come in handy.
Admittedly if you’re following a friend/corpmate who is mission running then things are different and a 4-4 salvage build will be more efficient then a 6-2 salavage build in that particular instance.