At what point would you step up to ferrea hollow stem valves

I installed longer 5/16 valves in my econo heads. The rocker stands were machined off when I bought the blown motor but had short valves. I am using T&D rockers.
I think we are getting off topic here. I never said that smaller valve diameters would break or that they cannot be reliable in a given
Setup. But if we agree that a hollow stem valve would be weaker
Than a similar diameter solid valve stem, then that same logic tells us that a larger diameter solid stem valve would be stronger than a solid stem smaller diameter. By some standards an engine that only runs 500 miles would not be considered reliable. How many miles do you think a pro stock engine sees. NHRA passed new rpm limits to lessen the teams operating budgets due to valve train component costs. Those motors won't see 500 miles before the valve train is serviced. Top fuelers even less, so like I said it depends.
The valve train setup is not really a sum of only one component, but of all the components in the valve train. Depending on the expected useage of the motor. IMHO