We know for a fact that the player's decision to have his PC take a rest must be paralleled by the character resting/avoiding stressful activity. The character knows that resting refreshes his abilities, even if he doesn't know the game mechanics of 5E.
They definitely are connected.
This is a poor analogy for what is happening in the game. It is not 'long rest followed by a short rest with no gap in-between', as some have suggested. It is a long rest, followed by stressful activity which tires you out, followed by a short rest to recover from that new fatigue.
A better analogy would be: watch TV for an hour -> do 300 sit-ups -> watch TV for another hour while recovering from all those sit-ups.
Now, back to the question you avoided: after 8 hours rest, we ask the DM, "Have we had the benefits of a long rest yet? Are we fully healed? Can we cast spells again? Are our spell slots/superiority dice/ki points back?"
You're the DM, Aaron. The answer is either 'yes' or 'no'. The answer cannot be, "It depends on what you want to do next". The body doesn't wait to heal until it gets a glimpse of the person's future intentions; it just heals over time. The state of a body is either 'wounded' or 'un-wounded'. It can never be in some quantum uncertainty where it simultaneously is AND isn't wounded, and where it only collapses into one state or another depending on what the PCs intend to do in the near future!
Your answer to the question (have we benefited from the rest yet?) is what we base our next decisions on! Not the other way around. You are reversing 'cause' and 'effect'. Your game world breaks it's own laws, just to mess with PCs!