Quite simply, there are no industry standards. At best, there are industry averages. Years ago, the industry tried to get together to set standards ( I was in the meeting ), and we came to a general agreement, but it was never implemented. Every manufacture has there own philosophy or reason for the specs they build their clubs to. They can, and do vary from model to model. As long as you know YOUR specs, you can play any brand you want. Titleist’s “standard” may be different from Callaway’s, etc., but if you know the loft, lie of your set, then you can match specs. Length, that is a little more difficult. Depending on how each company measures length, you can see variances. You can see variances from different types of measuring devices. So, before you change brands, if it is at all possible for you to compare “standard” lengths from one company to the next, I would advise it. You can do this by going to any golf specialty store like Golf Galaxy or PGA SuperStore and comparing the lengths of the “stock” sets on the wall. That could give you a general idea if there are variances in the standard lengths. I do happen to have the new Titleist irons in my office, as well as the Taylor Made P790 and the Ping Blueprint, all #6 irons. I just compared the lengths using the old fashion method of the rule down the back the iron and the Ping and the Taylor Made were dead on 37.5″. All the Titleist were dead on 37 5/8, so 1/8″ longer. The web sites list the Taylor Made at 37.5, the Ping at 37.25 and the Titleist at 37.5. So, you can see what we face as players and clubfitters. We, here at The Golfworks, do have our own set of standard lengths and they are listed on our website.
Hope this helps and gives you some insight and guidance.