That's one approach. Personally, I don't want any but experienced students coming close to a break position with any speed. They simply don't have the control for it. For immobilizations that don't have a break very close to them, those can be done with speed and full intent.
There's also the issue that "full resistance" is a problematic issue with some arts. The resistance I would offer is nothing like the resistance they're likely to get on the street. I can defeat most techniques with nearly zero strength (and eventually teach students to do the same). The theoretical attacker is unlikely to have that ability, so we have to actually add some simulated resistance. By that I mean offering resistance in other ways, besides the counters. An easy example of this is pulling the arm into a bent position with sheer muscle to prevent an Arm Bar. This opens some new opportunities - some of my favorites - that the aiki-based counters don't offer (obviously, there are different openings presented by those).
So, if I only test with 100% of my resistance, I would only offer the aiki-based counters, and students wouldn't get to learn how to deal with the more likely types of resistance. It's an aggravating issue, because new students could actually produce that resistance (it's what they're more likely to do), but they tend to try to hard, and put themselves at risk, so we bail on the technique and do something different rather than risk the injury.