You are correct that using ELocks is just one step of protecting units from walking off. in reality, if they want it, they can take it - don't forget that. (Think battery powered grinder with a cutter wheel on it.) The goal is to reduce the risk to a point you can tolerate, which means making the theft more troublesome for the thief, who is typically lazy, wants to do the deed rapidly, and doesn't want to make a lot of commotion in the process.
I use FOUR locks to secure a single unit on a RAM Mount. To me, one ELock on the gimbal isn't enough, so I use two there. A third ELock is used to secure the gimbal bracket to the top plate of the RAM Mount. (This ELock is a non-standard application of the same one used on the gimbal mount). The fourth ELock is one to secure the ball tension knob of the RAM Mount so they can't just loosen that and walk away with it.
The above still isn't enough for RAM Mounted units. On my installations, the ball base is always through-bolted using locknuts - never just screws. This means they'll have to get a wrench or socket to the backside nut to unbolt the entire mount for a walk-away. This challenge (under-deck or under-console) is starting to get complicated and takes too much time, so the unit is no longer easy pickins'.
Console panel flush mounts: Many factory panels are simply secured with 4 sheet-metal screws! A thief can easily zip those out and take the unit still mounted in the removable panel. A unit can be out in under a minute! I upgrade this to through-bolts with locknuts also, and may increase the number of bolts to make taking the panel way too much trouble for the thief. It's not easy getting a wrench or socket to those backside nuts up under the console. You could even put a couple of ELocks on the backside of such a console flush panel.