Is the light on your MagSafe plug glowing green or amber? If it's regularly amber, even after being plugged in for hours, I recommend depleting the battery (run on battery power only) to 20%. Then take it back to 100%. I have found that the battery doesn't blow through cycles while the plug light remains green, but mysteriously does when the light is amber.
I'm currently vexed by the same issue. I've been told by Apple this is normal. Optimized battery performance is smarter than me (I'd fully accept this reality, were it true.)
Third call to Apple was more of the same, but with an added layer of gaslighting.
I'm now taking daily screen shots like this to prepare for call #4 sometime this week.
Where are you seeing these varying opinions, Old Poodle? It's been so long since I've been left high & dry by Apple Support, I have forgotten where to look.