Adjective or noun for "uses rules that are commonly accepted even if not consistent"

• For elapsed time, you've got absolute. (Although I think elapsed itself might actually be better.)

• For clock time, you've got local. (Although I think adjusted might actually be better.)

For what people would consider to be a "a day" (5:00 p.m. to 5:00 p.m.), despite a time change either way that results in that not being 24 hours, I would use the word effective:

[Merriam-Webster]
1 a : producing a decided, decisive, or desired effect
      // an effective policy
2 : being in effect : OPERATIVE
     // the tax becomes effective next year

In some ways, this works better with the adverb effectively (although I understand you might need the adjective for classification):

[Merriam-Webster]
1 : in an effective manner
    // dealt with the problem effectively
2 : in effect : VIRTUALLY
   // by withholding further funds they effectively killed the project

In short:

At 5:00 p.m. tomorrow, a day will have effectively passed.

You can look up synonyms for effective and effectively. When I think of these words in this sense, I mostly think of practical and acceptably. Or essentially, which isn't actually listed at Merriam-Webster, even though that's a personal association of mine.