From my studies examining the #ADnD, RAW, it pushes not only for 1:1 downtime, but ALSO for 1:1 play within sessions of play as well. The evidence is in the 1e DMG, and also appears directly referenced, and similarly implied, in modules made during that time.

In the 1e DMG, 1979:
1:1 between sessions is recommended
Combat rules heavily imply 1:1/real-time as well, with 1 minute combat rounds, and if a player dithers for what to do on their turn for a whole minute, to skip their turn, as they are representative of their characters' inability to decide as well
Combat rules also describe that whatever players are discussing at the table during combat, can be heard by the local NPCs as well

In the Tomb of Horrors, 1978:
instructed to assume 1:1 time between sessions, to recover adventurer HP
1:1/real-time events, such as counting down from 10 as a door seals shut, are described

Throughout #ADnD, the design is to keep the decision space most closely in sync between the players and their characters, and how players decide to use their own time contributes to their success or detriment. In other words, immersion in time. "it is best to use 1 actual day = 1 game day"
#ADnD DMG, page 37