> R voters claim the economy is bad under a D president and immediately switch to claiming it's good under an R president.

adding on to this, typically it takes 1-3 years for the effects of an administration to really bear fruit in the economy, either good or ill. So a common tactic from the R side the last several presidential cycles is to claim ownership of the economy handed to them by the outgoing D president, then when their policies cause some kind of problem, blame the incoming D president 4 years later.

See also: who the R's blame the deficit on vs. which party's presidents actually increased the deficit the most over the last 20-25 years.