The best way to learn about tool life span (Carbide vs. HSS) is to do an actual bench test on it, there are a lot of factors in the actual test cuts, here in the shop were using 1/8 bits, for the HSS it only last 2-3 days on wood (8 hours / day) before it gets dull and needs resharpen, on the carbide side it can last 2 weeks (10 days) without worrying of getting dull, here in our area the cost of the HSS bit is 40 php and the carbide is only 60 php, since then I dont use HSS for mass production due to the hassle it gets (frequent resharpen and tool change) in the actual production.
one thing in mind, china carbide bits are more tougher now than the US carbide bits, the reason....I dont know, try and bench test it yourself to confirm.