I think "optimal" is a bad choice of words. It must be correct or it won't work at all.
I think you can encounter a problem if the wiring order is in the library, which may then require editing same. With the Henning Karlsen library the pin call is in the code just like a 16x2 and not a problem.
I get the impression that the contrast rather depends more on what is being displayed than the module. Thick digits and graphic stuff seem to be more trouble than they are worth. In the Stuart Lewis programme, the contrast control is on line 154, but I did not need to touch it. This may have to do with the display being called upon to do what it does best 12x6 characters, although this does not account for the chunky text on my 5110 phone. The PCD8544 library also does 12x6 text and I have never had to adjust the contrast. I assume there is a similar line in there for that and the same command will be found on other "no-library" examples.
I think the Henning Karlsen library would be the best way to go, but I don't know what arrangement he makes for contrast, as I have never used it.