I think it's BeeNo who has always said that you shouldn't look at the number of units but their military strengths, because for example even in the very end of the set about 50-75% of the units are infantry, but their total strength is only about 10-25%.
If we are talking about current situation, then there are a few thoughts on my mind. Indeed, right now infantry consists about 85-90% of total military strength. However this also means that most of the states are "inf hoarding" not only us and for that matter if there are no wars this is what most of the states do for the most of the set (considering the number of ships skyrockets only in the last few days). If we take for example last set then LoR's top went well over 200m inf with little/no defense, but I can understand that. I like to think about it as adopting to the current situation because upgrading too early can hamper your state and take away your chances to get the top spot. Also I find it somewhat pointless and it's probably more of a psychological thing if your opponents see that you have for example 1m lvl8 ships. Because on larger scale if someone wants that attack you that 1m ship makes little difference. It starts to change somewhere in mid-set or last third of the set, when your (top) state is strong enough so that there might not be any states that could break you even if they convert 100% to 1 unit type. Combine this with a few sleepless nights and some luck and you will keep your extremely balanced top state alive till the end of the set.
Basically I don't care about how other people are playing and I find that it's not up to me to say that they should play this way or that way.