As far as i’m concerned i play the same reed strength that sounds the best to me.

I get your point, you are trying to build up stamina/endurance for a gig.
What you are doing with reeds, you could do the same thing play with a harder size mouthpiece and then revert to your normal mouthpiece.

Instead of doing that – what i would do is work out the average time you spend playing a gig – say you gig for 1 hr only.
Then i would build up my endurance by practicing for 2 hrs solid, then when you hit the gig scene 1hr should be less tireing than 2hrs practice

only my 2 cents worth