From what I've seen republicans tend to ride the coattails of the person before them and *lay claim to what their predecessor accomplished. I don't know enough about that time period to say if that was the case then but it seems likely.
I’m happy to know that I’m not the only one who notices this. Democrats lay out a beautiful table with a wonderful meal for all, repubs come in and say “wow, look what I made!” And then proceed to have a food fight, after which a dem has to come in and clean it up. The one that I’m curious about is Carter leading into the 80s. Did he do things to set the economy up proper, or was it the result of a rubber band effect from the global economy being overall shit at the time.
That's just the way a lot of economic policy works. A policy's effects are not be instantaneous, but may take months or years before they are noticable depending on what they are. This lag often results in the next presidency experiencing the economic policies that were implemented by the previous presidency(s).