My DAN insurance has no depth limits.
The only time I saw a policy with depth limits, the limits of the policy were clear--130 feet. No guesswork involved.
I was recently looking at travel/medical policies, and at least one that I recall excluded coverage for scuba diving deeper than 60 feet. It also said something about the presence of an instructor--maybe it was deeper than 60 feet without an instructor present. In any case, it caught my attention. I don't care about that aspect of the policy because I have DAN insurance. But people really do need to read the fine print.