If the paint was air tight, and never opened, You should be fine...Now, in enamel, if the paint has hardened, of course You pitch it...Lacquer, add thinner, and You can bring it back...If You are spot painting, then You more than likely went over on thinning the paint, and naturally have a mismatch...If a viscosity cup is used, You would be OK...22 seconds is the right mix..

1952 Chevy 3104 Shortbed 5-window
Remember; Politicians and diapers both need to be changed
often, and for the same reason.....