It seems to be too broad to me.
the 3 most commonly used moderator training techniques used
Allowing for common sense to define "commonly used", how do we select the 3 most commonly used? There are university courses and degrees and seminars designed to teach leadership and training methods. Each presents a different view for what has worked for their audience. Answers could easily select a group of common methods, but each will select differently and present their arguments for why this is used effectively. For this reason, I think it is too broad
Do these techniques affect moderator selection
I'd hope the answer to this question was "yes", otherwise I believe their training needs to be adjusted. Moderator selection is a broad topic (appointing, community promotion, nepotism, elections, etc) combined with what training methods make selection effective makes the range of answers very wide. For this reason, I think it's too broad
This type of question is good, but I think it it needs to be narrowed in scope. Instead of asking for a list of common training techniques, ask about a specific one you are curious about.
How does a formal training session with new moderators improve their ability to moderate in a community? Did [site that uses this technique] notice an improvement in moderator behavior after this training was implemented?
On the job/tossing into the fire training of new moderators is relatively common in smaller communities. As these communities grow and add more moderators, does this method of training scale well in terms of consistent moderator actions across the team?