This may be a bit basic but I want to confirm my thoughts: When in different ad groups, keywords: "best medical billing" and "medical billing" will compete with each other's bid when the searcher types: best medical billing Therefore I need to choose if I if I want to bid on the root words or the long tailed version(s). Am I correct?
They will if "medical billing" is on phrase or broad match, (not if [medical billing] is exact match) - Google will choose the one that has the best quality score / ctr.
you can add medical billing as exact negative to the adgroup that contains the keyword best medical billing