Pedantic
Legend
I don't think that can be true. The room with stuff in it sure, but the character looking for spellbooks and not doing handstands, or brewing potions or whatever else they opt to do is entirely down to the player. We can probably map out the time searching a room takes, and point to the 5 minutes of time in that room and clearly point out which things were down to one player's choices, and which were down to the GM.If my declared action is "I search for spellbooks" and the GM decides the answer to that unilaterally ("alone"), whether by consulting their notes or making up what they think is "logical" on the spur of the moment, then that absolutely is a railroad. The GM has decided everything that happens.
You could have (an admittedly very boring) game session that was nothing but a massive library keep, devoid of anything but romance novels, that a character wanders through looking for spell books, evaluating room by room. I'm pretty sure that could be handled much more easily/efficiently by noting the time that would take and moving on, but it certainly would still happen, and be different than if the player had decided to stop after the first room. If for no other reason than after that's done, I'd start describing the scene outside with a different time of day.
You're adding some kind of relevance criteria here to "things happening" that I don't entirely understand enough to define yet.