Chaosmancer
Legend
I think I have been misunderstood by a couple of posters.
DMs who change up the rest periods (including utilising the alternatives in the DMG) do so specifically and intend for certain spells to lose some of their functionality. Those are intended consequences.
There was a massive thread (200+ pages) which discussed this on Enworld 2 years back about how the 1 hour and 8 hour rests are easily circumvented by using spells such as a Rope Trick and Leomund's Tiny Hut.
One of the many solutions suggested was to change up the rest periods. It is very much known.
You cannot exactly have a gritty campaign when spells bypass any measures taken to make it gritty.
Hence TwoSix's quote
Right, I get for some DMs, they fully intend every consequence of their actions.
But, in this very thread, we have Oofta who said they changed the rest periods because they wanted to change the encounter design because of (what I assume) narrative reasons. But they do not intend to change Mage Armor from a spell that Wizards can cast for cheap as an improvement to their AC.
For me, if I changed the rest variant, I wouldn't have thought of Mordenkainen's Mansion. A 7th level spell suddenly turned into a quick way to get a short rest. Way weaker than it was intended, and honestly, I feel kind of worthless in that case. Which is a shame because you can have some good humor with that spell.
Hence, my reply. Because not every DM intends every consequence when they change something. Maybe they did it for an entirely different reason than weakening spells meant to aid in resting, and realizing those spells are affected is something they would like to reverse.