I've heard it said that Sparta's military was unsuccessful, but is this really the case when we take into account the various factors that might have worked against them?
Were they facing superior enemies? Were their foes able to wield larger armies? Were their enemies more technologically and logistically sophisticated?
Did the Spartans have a geographical weakness that might have given their enemies an advantage against them? Was their land less economically productive than that of their foes?
I guess the question I'm trying to answer is: did the Spartan military system hurt or did it help? It seems clear that their win and loss statistics in battle can't tell the full story about their system. It's not like any other system of societal organization would have helped them defeat the Persians and expel the Romans when they came knocking.
Although this doesn't directly address your specific question this old thread: https://www.reddit.com/r/AskHistorians/comments/6rvusy/is_the_military_worship_of_the_spartans_really/dl8ns8q/ by u/Iphikrates which was recently linked should cover all the information you need. It breaks down what specifically was good about the Spartan military, and what wasn't.
Short version: Good Hoplite phalanxes, slightly more drilling than other city-states, lousy at everything that wasn't heavy infantry.