The topic of how much stone-age men shot their arrows, spears, atlatls, etc is an interesting one. The best example we have is Ishi...although we have observed many primitive tribes in recent years as well. In all cases the act of shooting is a lot like spending money.
Spending money is an important activity, but once we get the hang of it, we don't really spend much time playing games that teach us how to spend it better...especially if those games cost money. We get into a routine of make-money-then-pay-for-necessities and there really isn't much deviation from the pattern that we develop in order to survive within our little niche in society. The same is true for arrows and other ammunition that gets "spent" as it is used. The more you use them the more you spend...and the more you spend the more you have to make.
There are many other activities that take up lots of time, when living in a primitive way, that are very important to the warrior and hunter as well. Travel, finding materials, setting/checking traps, guarding borders/territory, making/drinking "funny" beverages, etc,....not to mention the task of chasing/courting/supporting women.
Also, in modern times, if you consider how much soldiers actually fire their weapons when deployed to a combat zone you will see that they tend to be conservative. And when they have time off they don't usually go down to the firing range. Also, you don't want to be surprised and caught empty-handed because you spend it all at target practice. And if you have to make you own ammunition, well, then being conservative is a no-brainer.