I use a torque wrench on those EBB bolts. As I recall, I set it to 10 or maybe 11 Nm. The torque wrench is not really big, so I don't get a huge mechanical advantage. 10 Nm is not super high torque. I would say that using that wrench that came with my Nomad, a good firm twist is about right. I wouldn't go getting my body behind it!
The size of the dent is definitely closely related to the torque, in the range of 10 Nm. Not sure what happens if you go too too high. Ultimately deform the whole structure of the EBB, I suppose. Before that maybe just make dents that are too big so you end up with less closely spaced indents.
Thinking about it a little more... when the axle is at 12 o'clock, the mid-point of the travel, the bolts are hitting the thickest strongest point of the EBB and also the chain-length change per degree of EBB rotation is at a max, i.e. the dents need to be closely spaced. Toward the extremes, 3 o'clock and 9 o'clock, the EBB is thinner, and the chain-length change per degree of EBB rotation is dropping to 0. So the dents will be more widely spaced. There ought to be a nice conclusion to all this logic but right now it eludes me!