Multiple axis settings for Feedrate, Acceleration, Jerk-HOW DOES IT ALL WORK?

I'm a bit confused and also Lazy LOL so rather than messing around with settings, I was hoping someone smarter than myself could explain.

Marlin has the provision to set these things individually for each axis but when G-Code is generated for a file these is just 1 Feed Rate that the entire system is commanded to run at. Am I correct so far?

So, if that is the case and you have drastically different settings in the firmware for different the different axis (i.e. I have to set the acceleration for my Y Axis much lower because it is moving so much weight it will rattle my machine apart if I do not). How is this interpreted when my controller is spitting out commands to my motors?

Are we limited by the on axis that has the lowest Max Feedrate?

It's great to have so many option to control speed but, I feel like I could optimize my machine's performance is I understood this better.

Many thanks in advance for anyone who can offer up some insight!

Essentially it depends on the move. If you're moving in just one dimension then the printer can theoretically achieve the maximum jerk/acceleration/speed on that axis. But when it's moving in more than one dimension at once (and yes, the extruder counts as a dimension) it has to figure out which is the most limiting of those settings. So suppose your X axis can move at 100mm/sec but your Y can only move 20mm/sec. A 45 degree diagonal move will only move at 20mm in both axes (for 28mm/sec total movement along the diagonal) because the speed is limited by the Y axis. However, if you're doing a move that's 20 degrees off the X axis, you can theoretically move at about 58.5mm/sec along the diagonal for an X speed of 55mm/sec.