This is absolutely true, but there is a strong counterpoint: You also learn the limits of your own systems and how to operate them most effectively yourself (and better than adversaries can, too).
Just to pick a recent example: Russian air defense in the early stages of the Ukraine war was dismal (more specifically: defense against big, slow drones like Bayraktar), despite having sufficient AA capability "on paper"-- the war allowed them to visibly improve.
I'd expect much more value from validating and improving your equipment and its handling than the actual "cost" of revealing its capabilities to adversaries in almost every conflict.
Practise is good, but exhaustion is bad. Russia is getting exhausted, which is why their influence collapsed in Syria, Azerbaijan and Armenia, allowing the US to overtake those vacuums.
The US in WW2 staged their 20th century by letting others (China, South East Asia and the British/Soviets) get exhausted first. This was more an accident of geography rather than US grand strategy, but it worked all the same.
The defense against Bayraktar at the beginning (the big column to the north of Kiev) was dismal because AA assets were turned off, not because they were unable to shoot Bayraktars.
The problem was command and coordination.
Darwin worked and Russians learned (as did Ukrainians).
Regarding your last point: In peace time, you want to prioritize hiding your true capabilities (perhaps inflating them in (misleading direction) to deter them from attacking). Once the ware breaks out, you want to improve your capabilities as fast as possible.
Definitely, you have to weigh the benefit of experience against the cost of revelation. (And all the other costs of course.)
> I'd expect much more value from validating and improving your equipment and its handling than the actual "cost" of revealing its capabilities to adversaries in almost every conflict.
That depends on how far out of touch your reputation was with the facts. If you're not able to live up to your preexisting reputation, being tested is all downside even if it improves your actual capabilities.
>much more value from validating and improving your equipment and its handling than the actual "cost" of revealing its capabilities to adversaries in almost every conflict.
The value of carrying a big stick is lost when others see the stick breaks after a few swings. There's value in maintaining military kayfabe - revealing hand in sideshows and losing deterrence for main events as result can be much costlier down the line. What was learned that wasn't already known and deliberately avoided in polite conversation?
"Data moats" are a problem for military tech, too, I guess.
There is no amount of math that can make up for the lopsided dynamic of hypersonic missiles. The only reason the “iron/gold dome” con job was even plausible to plunder trillions in U.S. Monopoly money was because missiles were crude, slow, and not MIRVed or had decoys at one time. That was a long time ago though.
MIT Prof. Emeritus, Theodore Postol, has been trying to warn about this basic, mathematically proved fraud for many years now. However between the indifference because the party was still in high swing and the plundering was making people rich who could pay professional lobbyists/liars, very few people were paying attention or really cared, even though it’s clear fraud and just a false confidence; as is the objective of a con job, which comes from “confidence trick”.
There are several lectures he gives and more recent appearances on various YouTube channels where he clearly describes the inherent fraud in “missile defense”.
Here’s the synopsis; it’s like trying to prevent sand from hitting you once someone has thrown a fist full of dry sand at you.
It’s basically just the end game in a long history of American snake oil salesmen turned missile defense salesmen. You get useless junk, they run off with your wealth.
There is an assumption here that the value in improving defenses is the same as improving offensive weapons. That is not the case in the assymetry that drones provide and Russia is the first example.
Russia has not been able to improve AA capabilities to the point where it's "safe", for any definition of the word, neither has Israel. Israel and Gulf states often tout over 90% interception rate yet it's really at the mercy of Iran to not target their most vulnerable sites. If Iran was routinely targeting desalination plants and refineries it wouldn't matter if it was 99%: one hit is all it takes. Similarly Russia cannot keep Ukraine from targeting their oil infrastructure.
Air defenses need to be 100% to prevent physical, economic and moral damage. That is an impossibility.