That's a good question. There are a lot of resources on this site, looking info on stim tolerance, I found this:
I have lived among coca-using Indians of the Andes and the Amazon basin in Columbia and Peru and have not seen any signs of physical deterioration attributable to the leaf. I have never seen an instance of coca toxicity. Nor have I observed physiological or psychological dependence on coca. Even life-long chewers seem able to get the effect they want from the same dose over time; there is no development of tolerance and certainly no withdrawal syndrome upon sudden discontinuance of use.
Disclaimer-I have much more cocaine experience than amphetamine. Cocaine tolerance, especially coca, reminds me a lot of cannabis tolerance. In one way, you get just as high everyday, in another way, that dragon we chase, gets away.