A couple of team members and I recently gave a talk about accessibility to our in-app assistance team. My section summarizing my point of view about Human-Centered Design is about 6 minutes long. https://vimeo.com/714244608/441eb9c869#t=0h02m46s
While we always aim to create systems that need minimal training, there seem to be some products that are best to optimize for intermediate and advanced users, and then offer support for onboarding and getting up to speed for day-to-day use.
At Moody's, I designed and implemented WalkMe training for ImpairmentStudio, which is a product that banks use to calculate their allowance. This value impacts their reserve, which is the assets that banks hold onto to offset risk in lending.