The F-106 was used in its designed role up until the early 80s. When it was replaced in the Fighter Intercepter Squadrons it was often with F-15s.
For example the 48th FIS at Langley AFB recieved F-15A&Bs primarily from 1TFW which was beginning to receive F-15C&D models. Other planes from Langley went to other F-106 squadrons
So I think the F-106 did run through a pretty healthy life cycle. It was designed for a pretty specific role, did that role very well.