I don't know what the official name of this phenomenon would be, but from the development of my own company (and also too much civ4), the problems with "chance" is that you "built that axeman" for a very specific reason, at a very specific time (turn), while sacrificing i.e. not building building something else, like a worker or granary. "Having that axeman" is probably a key part of your strategy that you already built up around "that axeman" existing. If you lose "that axeman" to whatever odds, it's bad.
Thus, from an investment (cost) perspective, and it also applies to civ4 units, the "safe" way of doing it – if you already stack odds in your favor – is by "counting on it costing one and a half". This is also because it's very hard to retroactively ask of anyone (in business from a paying client, in civ4 from a city) to change their own plans. If the odds are *not* in your favor, the multiplier is x3, rather than x1,5.
Thus, if you *need* two axemen, you *must* build three. Even at favorable odds, you are planning on losing one.
If odds are *not* in your favor (lets say enemy axe vs your flatland archers), you need 3 archers. One to die, one to be badly wounded, and one remaining at full health after the event (thus continuing to serve its role without need to retreat).
The trick is to make investments in a way that guarantees their utilization even if it turns out that excesses are not needed. For example, deliberately lacking a city garrison in a nearby city, so the surplus axeman can fill that role if needed. This way, you "lost" only 20 hammers (since 15-hammer warrior is a valid militia, and an axeman costs 35). What you gained, however, is far more valuable, and that is that the rest of your empire can go as you planned, with no need for panic-whipping and the like.