An rpg campaign has the obvious transitions. As player characters move from being level 1 to level 20 there are new abilities, more hit points, new spells and new monsters to fight. However, there are more subtle transitions that a good DM needs to be aware of. Doing so allows a DM to let these transitions occur naturally without trying to adhere to earlier methods of campaign management that no longer effectively work. In addition, these transitions can be utilized to highlight the progression of the player characters.
As an example of this there is time, specifically how it affects food. At level 1, food is an issue PCs need to be aware of; food is usually kept track of very carefully. It is a tension mechanic; will the characters have enough food to be able to continue? This is because at level 1, the characters' main resource is time. After a battle the PCs use their resource of time to heal up. They also use time to regain other tools such as spells.Without the expenditure of time the PCs are ineffective. Food plays into that time constraint. It is a visible consequence of spending that resource of time. The longer the party rests, the more food is used.
However, as PCs gain levels and more resources, the resource of time becomes supplanted by those other resources. Spells, potions, and magic items replace the need to spend time to recover after a fight. PCs have more spells to cast in a given encounter and thus by sheer volume will be able to continue to the next encounter without being depleted of spells; the need to rest does not occur as often. The need to rest to recover hit points becomes negated by potions and magic items (the ever popular wand of cure light wounds) or just by dint of having a much larger hit point pool. Time no longer is resource in as high a demand and thus other considerations, such as food, become trivial.
And that is where a transition comes into play. The PCs should no longer need to keep tracking food. If a DM continues to require the minutia of food tracking at high levels, it has turned from a tension mechanic to a mechanical annoyance. The tracking of food will quickly becomes tedious at these levels and that feeling of the tedious will begin to pervade other aspects of the campaign keeping it mired in the past instead of allowing it to change into something better.
Instead of making the players keep track of how many rations they are carrying, simply require a a weekly or monthly food expenditure...or go the extreme route and simply state that meal purchases come out of loose change the characters carry; after all, at higher levels characters have access to thousands and thousands of gold and requiring them to spend their gold in such miniscule amounts becomes burdensome. Instead of requiring Outdoor Survival rolls to find food for the party, the DM can hand-wave the roll and simply state, "Because of your much greater experience in the wild, you easily find enough food for everyone while you travel."
The side benefit of allowing for this sort of transition is that the players now have a visible sign of progression. Where before eking out food while traveling was a challenge in itself, now the players can see how they have tamed that aspect of the game. The feeling of epicness begins to enter their sphere of play...and that is a good thing.
Hopefully, I've given you some...(/puts on shades)...food for thought.