WOT in the hangar

It shouldn't as it would only open the butterfly valve in the carb throat. For decades owners leave their throttle shut with the springs in tension and they don't really have issues.

It might leave a way for the cockroaches to get in the carbs though. LOL :)

I love this question, its comforting to know that others out there overthink things like I do!   However…

A well designed spring installation typically operates with forces below 50% of the springs yield strength, so they don’t typically deform when held in a loaded state.  When held in a stretched position within design limits, the energy required to stretch the spring is stored in the spring, then used to return the spring to its normal shape once the tension is released.  

If the spring is operating within its design limits, the number of cycles the spring is subjected to actually plays a greater role in degrading the spring than being held in a stretched position (within its design limits).  So I guess you could make a case that opening the throttle after each engine shut-down may in fact degrade the spring more than just leaving it stretched.  

The other mechanism that may deform a spring (that is held under load) is called “creep”.  But with a steel spring, creep will not typically occur in the absence high temperatures.  This can happen over time with springs used in high heat situations, like the exhaust system, but I would not give it a second thought regarding the throttle spring.   Sleep well.