With a spare that has been patched and stored at least yuo know the tube was once good.

New tubes also fail.

I'd go with inflating and leaving overnight or better still all week. That way you know. I also always carried 2 tubes and a patch kit.

Think about it, one patch of thorns and yuo may have 2 flats with multiple punctures. Never got that unlucky, but on my first double century less than 25 miles in I gave one of my 2 spares to a rider on his 3rd puncture.