You can’t know everything
Circumstances for making are constantly changing — equipment, knowledge, materials, and other Constraints are different from scenario-to-scenario and from year-to-year (or lately, on places like the web, week-to-week or even day-to-day). A Good Teacher acknowledges they won’t be able to answer every question, keep up with every new direction, understand every tool, or know every available solution. This is fine. A good teacher is transparent when ignorant, and offers avenues for exploration or further help from elsewhere (perhaps another colleague, the right book from the library, a lead from social or art history, or a well-crafted google search). Being a professional isn’t about knowing everything, it’s about remembering how to find and ask for help.
And! But! Everything Is Connected