Well, yeah.

That is somewhat affected by WHO the manufacturer might be. Nowadays we're mostly assembling ARFs. How many sets of instructions have you seen that were screwed up here and there? Especially the ones that come with the "you get what you pay for" ARFs. And how many have you seen that were copied from the ARF mfg's previous models?

Like everything, it depends. How much you trust the mfg, and how much you value the work you're putting into the model. Truth is, with the importance of the CG why bother making a judgement of who the mfg is. I check my own work, why assume anything.

It takes me maybe 10 minutes to measure the model and run the numbers. And I get an absolutely reliable RANGE to work with. It might be the most valuable 10 minutes spent on the model. It often saves me a bunch of time and lead when balancing. And certainly insures that the CG location will help the model, not hurt it. And I get a feel for what I'd like to do with the mfg's suggested throws.

We often get more out of our models than we put into them.

BTW, do you know the rule of thumb, "measure twice and cut once"? Why do that? You measured it once already. Isn't that good enough? Why check anything? Same concept with taking the mfg's word for it.