Even without limits, you're never going to be as efficient as someone who fixes the same failure every single day. I've certainly fallen into that trap before. Sure, I got it fixed myself in the end, but in hindsight I'd have been back in the field a lot sooner if I had simply brought in the expert. When time is of the essence, putzing around trying to fix it yourself is not the optimal choice.

And that's not even considering the need for parts. Driving all the way to the dealership and back to get the parts you need is much more time consuming than the dealership tech bringing the parts with him when he comes. He only has to travel half as far as you do.