I’ve also noticed that a few of my shorter clubs, mainly my 9iron and PW are going shorter than what I’ve charted.
I would say clubs play reasonably consistent the vast majority of the time... but you will experience shots that seem like outliers. But you will also experience shots that may seem like outliers but are more reflective how your club/ball combination plays on certain holes in certain winds... that too is something to learn.
It can be too nuanced to try and explain every situation, but as you are doing, the key is at the very least starting with known yardages you feel are consistent.
When you experience what may be an outlier in a certain situation, take a note, but don't change anything yet. Try to replicate it or watch for it in a similar situation. If it starts becoming consistent, then that hole, that wind condition may play different than normal.
The game is designed to have variance, so it can make it even more challenging to figure out... also.. lower level clubs will tend to have greater variance than higher end clubs... hence the idea of getting players to upgrade.