When pondering training possibilities, the question for me is “Go deep, or go broad?” I tend to go deep (into one approach) when I find something especially resonant. When I was younger I wanted to know everything from everyone yesterday (going broad rather than deep), but now that there is less pressure on myself to do that, I see that I do well with going deep into one approach.
I have been fortunate to have four master mentor voice teachers. I found that I had to work with them serially. Any overlap got confusing. Latching on to a new approach in order to learn it well takes nothing away from past experiences. It all gets mixed together, trimmed, digested, and purified. Sometimes a long-abandoned concept is raised from the dead because NOW it makes sense! Something that a teacher introduced 20 years ago might have needed a future teacher + more experience in order for me to understand it.
Non-examples are also rich learning experiences. This sometimes includes classes and lectures by accomplished people, including former singers, recognized pedagogues, and voice scientists. These are fine people with rich experiences to share, but I was unable to glean help with my teaching from what I experienced in their classes. They helped me see some things I’d like to avoid, hence I refer to them as “non-examples”.
It may be that some of my best mentors are some of your worst and vice-versa. Consider exploring in yourself how much you can learn, and how quickly. Please don’t kick yourself for doing it slowly. Even when you are standing in front of a huge buffet, it may be the most healthy to put three items on your plate and savor each bite slowly.
It is actually a relief when you start to realize that for YOU, all approaches are not equally valuable. You’ll never know what’s what if you don’t go deep enough. If your budget or other life circumstances limit how many trainings you can take, then there’s your answer: Go deep! It’s cheaper.