I generally do not use time sheets, I talk to the guys doing the job and make an over-estimation of the potential time used to make sure we over-protect. Again the risk assessment and tool use is a small part of describing the activity / tool use and does not have to be precise, far from it - but you should err on the side of caution ot be sure.

Using your point on future mitigation. What do you think would happen in your example if you had all this data, all of which must be handed over to the claimants solicitor, and showed out of 100 uses, 1, 2, 3, 5 or what ever times the user had exceeded the limit?

I can hear it already - "The defendant routinely exposed my client to unsafe levels, and he OWN data even proves it!"

Or does the tool simply stop working at the (already stated unsafe) action / limit level - this definately would not be popular with the user.