I have no idea what you mean here.
It is true that when dealing with no decompression diving, different computers with different algorithms will give different NDL times, but as is taught in every OW class, even ones that teach tables, you simply go with the most conservative computer in a buddy team.
It does not matter whether you are using tables or computers--it is likely during part of an ascent that some of your tissues will be ongassing while others are offgassing. That's due to physics and is true no matter how you are measuring your dive.
I have absolutely no idea what you mean when you say people would have to teach different ways of diving. Can you give an example?
I thought I had given the examples. But, let me try to rephrase it, let's consider two computers, one will be the same model as mine, an Excel 3, I don't know which model it uses, but it is the classic ascend and stop model for degassing, anything bellow the degas area(~5m) is on gassing.
The other is the Suunto tha uses the model I linked in the other post, it uses a model were you make an gradual ascension were the degassing occurs in stages, the diver must ascend in such a way that makes him always inside an area delimited by an floor and a ceiling which are calculated by the computer according to the model.
Now lets buddy two people with those computers, they dive till near the NDL and decide to ascend, but which is the proper way to ascend to keep budding? As they are near the NDL, the excel will penalize it's user for ascending slowly with the Suunto, but if they ascend in the conventional way the Suunto will shut and will refuse to play anymore.
At the stop site the excel will demand a greater stop due to the ascend which for it was on gassing whilst it was degassing for the Suunto which will possibly award extra credits for it's diver for degassing.
Also, if you read the paper, you will see that Suunto do not consider varying level as just the sum of the different levels, it penalize the diver for changing depths as it(according to the chosen model) causes nitrogen bubbles that become difficult to expel from the divers body.
So certain classic rules are different if you dive with certain computers, in the case of the Suunto, the rule for degassing is not ascend and stop for 3min at 5m, it is ascend as the computer tell you to do. On the other hand it is valid for the Excel.
The rule: dive according to the more conservative computer becomes muddy as the models become complex as it become difficult to judge what is more conservative, the the example case, who is being conservative regarding the ascend? The Suunto or the Excel? For the Excell the slow ascend puts its user dangerously near the NDL as for him it still counts as on gassing. But for the Suunto to ascend faster would put it's user at risk as the nitrogen bubbles(according its model) would be forming too fast and becoming too big to be expelled.
Some can say that the best would be slow ascend plus stop would solve the problem, but it may be that for a sum of factors the Excel user really is too close to his NDL, due for example to a deeper dive profile and what if the slow ascend puts him in NDL?
There is no such thing as dive according to the more conservative computer if they are different, for being conservative for one can be risk taking for the other, this is a loose rule that only really hold if you take in account simple factors like different depth profile and water temperature.
In the example given, the only way to guarantee proper ascension would split the buddies, something that I particularly dislike, I am all for if you are budding you dive together all the time.
Also, if you look at the example given, the Suunto model is a clear case were what is taught in the OW regarding ascension does not hold, so if you are teaching a class to use this computer in particular, you wont teach the classic ascension and safety stop, you would teach gradual ascension. You would also teach that an square profile gives you more bottom time than varying depth profile.
If it were a class about E3, you would teach ascend and wait for computer clearance and that a non square profile would give you longer bottom time than if you did all your dive at the max depth.
It is true that in decompression diving, using different computers CAN break up a dive team if they give different times at different stop depths, but almost all modern decompression computers will allow you to overcome that and follow the more conservative computer. This thread is also not about decompression diving. If you are interested in how to dive different computers in decompression diving, there was a thread on that topic recently in the tec diving forums.
I guess I am many years away from decompression dive, one step after the other and let's make them baby ones. =)