I've made similar test a few weeks ago with one cheaper springer witch is Crosman Copperhead. So that is my conclusion:
s it ok? Probably not so much - that is what we hear from pros and semi pros that shoot springers for 20-30 years. But my porivate observations are some what different.
Im a springer shooter and airgun fixer/tuner from Poland and several days ago I made a little experiment (detailed description of it is here - text in polish:
http://zwiatremwlufie.pl/rozne/zmeczenie-sprezyny-wiatrowki/ but you can use g translator:
https://translate.google.com/translate?sl=pl&tl=en&js=y&prev=_t&hl=pl&ie=UTF-8&u=http%3A%2F%2Fzwiatremwlufie.pl%2Frozne%2Fzmeczenie-sprezyny-wiatrowki%2F&edit-text=&act=url.
In Poland we have 17J limit and my friend came to me with brand new Crosman Copperhead (it is a dirt cheap piece of ... chinese machinery with american branding) and it was much above 17 joules. Diagnose: cut your spring. But my friend lend me that rifle form little experiment - i figured that I will check how fast spring will lose energy if I will leave it cocked.
So:
1. originaly - 279,3 m/s (all test made on JSB Exacts 4,52mm average from 10 shots
2. after 6 hours cocked - 273,2 m/s
3. 17,5h cocked from last shooting - 273,3 m/s
4. 3 days cocked after last shooting - 272,6 m/s
5. 16 days left cocked after last shooting - 270,2 m/s
So conclusion is - it shouldnt change to much if will leave your springer cocked for 30 minutes. If cheap chinese spring in crosman did not let go - german in HW or AA should also. Reason why before people said that it will ruin your spring is probably because now we just have so much better sprongs in our airguns.