But how do you create a scenario without "nap time" consistently in the presence of Rope Trick, Teleport, Leomunds Secure Shelter, Mordekainens Magnificent Mansion and many more? Just ban the spells?
In my opinion, 3/4 of the reason for the 15-minute adventuring day is that it's not annoying enough to rest in D&D. Even in Neverwinter Nights, where it just takes 20-40 seconds and being reasonably far away from hostile monsters, you don't get people napping after every small group because that slooooows thiiiiiiiings doooooown.
Part of my group's unwritten rules are that I generally allow the characters to rest for free between sessions - it's the assumed default unless I specifically instruct everyone to record their current HP and ability uses - but don't typically allow the party to rest during a session, especially not with a one-liner like "I Greater Teleport the party back home, rest for 8 hours, Greater Teleport the party back to exactly where they were, and go through the south door."
But no, I haven't banned any of those spells or changed any except for Rope Trick, which I altered from "Target: One touched piece of rope from 5 ft. to 30 ft. long" to "it works like Mordenkainen's Magnificent Mansion, so don't be a rules lawyer."
If there is no time limit, just the threat of random encounters or assaults at night, there is also another "easy" trick. Just don't exhaust all your reserves. Just enough to take on one or two encounters, and leave the rest for the night and wandering monsters.
Uh, so if you take on two encounters and then assassins in the night, that's three encounters before resting, which is hardly a 15-minute day...
But yeah, usually the heroes are trying to do things which are a matter of urgency in my games, because that's what makes them heroes. Part of this is that I'm a terrible dungeon designer, so I don't have very many holes in the ground for the heroes to meticulously explore.