25 yrs ago!Who uses tables for diving? Show me where people write down the dive plan for every dive.
Virtually everyone uses a dive computer nowadays. These have different algorithms which all result in different NDLs for the same dive: Buhllman + GF (which GFs?); RGBM (which 'P' setting); Other proprietary Suunto algorithms ('P'?); DSAT; et cetera.
All fine if you're doing shallow dives, but as soon as you get to around 30m/100' and especially on air you can easily exceed the NDL with a single tank. Now add in differences between diver depths, even a metre makes a difference to the NDLs
I believe most OW classes are taught using computer(could be wrong) nowadays. And I hope the instructor will point out to the student that various algorithms are being used in dive computer( even from the same manufacturer eg Oceanic) and the resulting NDL is completely different
I dive with two different brands of computer with different algorithms and the difference can be quite substantial.