Also if you use the planning mode on your comp. You will be able to plan the dives to the max ndl for the algo your comp is using. And compare that to the rdp for your PG. Also as an instructor I would Highly suggest that when you plan your dive, You dive the plan! Comps can and do fail at the worst possable times! So if you have a failure you will know what your plan called for and if you have a dive watch or alternate comp you can surface do your surface interval get your computer going again and continue diving. You always should know within a min or two how long youve been at depth.