So you went from an old dead/weak battery to a new larger battery. Now you saw faster cranking. Impressive.........
My flashlight is really dim. I put new batteries in. Now I can see better. I should of put in larger batteries with the SAME voltage as the OEM batteries. Really shine so much further away. Come on guys.
You continue to demonstrate that you don't understand lead acid battery tech.
It's not the same voltage. A smaller battery, all else equal, drops to a lower voltage during cranking, and this (again all else equal) decreases its lifespan, before even considering it had a lower viable lifespan to begin with because even if the degradation rate were equal, starting with a lower CCA battery means the same % degradation, makes it drop to a lower (than needed to start the vehicle) capacity sooner.
The more it degrades in capacity faster, the lower the crank voltage is, and the faster still it degrades.
In fact the same is somewhat true of flashlights. If you have a high power flashlight, say a 1000 lumen light and are trying to run it from a 14500 cell, it will be dimmer than if running from an equal quality 18650 cell because despite their nominal voltage being the same, that is rated at a specific load and the smaller 14500 cell is rated for a lower load to meet its capacity spec, will droop more under high (or really any measurably different) current draw.
The greater difference with lead acid is this additional voltage droop, causes a more substantial permanent decrease in battery capacity.
Further, since the larger battery keeps a higher voltage longer, in a flashlight you really will see it shine further past the half life of the cell capacity, where it is depleted below the optimal forward voltage of the LED plus the forward voltage drop across the LED driver circuit. Battery voltage is not constant, it drops as the battery drains. A higher capacity battery keeps voltage higher at the same drain rate, unless there's a construction difference that causes higher impedance.
Ultimately with your flashlight analogy, it is more the same than different. Your battery will be depleted sooner and leave you scrambling in the dark, similar to a vehicle owner being stranded sooner because their vehicle won't start.