Ok so Mr 13 has passed his OW theory.Hes done 3 DSD dives with a decent instructor.
Im really keen that he should actually USE the dive tables in the 'real world" during his JOW training so it has become a habit to calculate his loading.
The instructors are bemused at this idea.
Whats wrong with my thinking?
Nothing is wrong with your thinking. Knowing how to use a dive table is an important skill. If we only rely on computers, then if our computer fails us, we can't dive. Having dive tables as a backup can at the very least allow us to make a repet dive with reasonable bottom time, and a concept of NDL.
Even though dive tables assume square profiles, and are limiting compared to a computer... Its better than not diving.