Here’s my non-scientific pragmatic approach to it......

I’ve seen numerous vehicles through the years suffer from the “bottom hose sucked shut/engine runs hot” scenario........ where adding the “spring” fixed it.

It’s a cheap and easy thing to try........ if it doesn’t help, you’re not out much time or money.
If it does...... it was a simple cost effect solution.

If you’re having issues with the lower hose getting sucked shut..... it certainly can’t hurt anything to try adding the spring.