Firstly, I agree with
@greeneyes statement about palate fatigue and blend choice 100%. Second, I've noticed some blends don't taste right until after the tin has been opened for a day or 3.. Not talking about drying or anything, more like letting a bottle of wine "breathe". Some blends are okay as soon as you crack the seal, but in my experience most are somewhat muted at best, bitter bitey hot air at worst. I give 'em all the same "grace period"... 3 days to rise to the occasion. Unless they are aged over 10 years.. even then, breathing can do some good as long as it hasn't already become mummified.
*opened, as in seal cracked and lid put back on. I'm NOT advising to leave a tin wide open to the elements for 3 days!!!