External provider

When do you use external service provider? I tried following:

  • To provide commodity infrastructure services - in progress, think will work
  • Commercial offerings without mixing in people from your company (defined scope and budget) - failed
  • Fast experiments to validate options (no integration with platform, no involvement of internal people) - success
  • Commercial offerings with heavily involving teams from your company (not fixing scope, but only cooperation period) - success
  • Bringing in industry accepted expert for knowledge sharing, problem solving, review (short-term: up to 2 weeks) - success