This has been bugging me for a while. In the hospital research there is an upgrade called Temp bed..

This has been bugging me for a while. In the hospital research there is an upgrade called Temp bed which increases wounded by a 10-20-30% etc. My question is when you reasearch it does it always add this % to your wounded capacity every time you increase wounded capacity? Or does it it add it once and that's it? Example: 100,000 max wounded. Increase 10% 110,000. Then when you increase max wounded by a certain number you multiply it by 10% more troops.

This is making me think to upgrade medical facilities before temp bed.