Which is of course, nonsense. In D&D the tactical choice, from the parties perspective, is to always go nova and then rest after every encounter.
I have always seen it as the DM's responsibility to give the players incentive to follow them, but I suppose that is a bit of reading between the lines.
The 5E is a lot more explicit about how many encounters the DM should place in each day.
That was specifically in response to someone saying that it is I, not the DMG, that came up with the idea that players should need to expend resources, and I was pointing out that not only does the DMG say that, it actually takes a step further than I ever would by saying that something MUST require resource expenditure to provide XP.