There's a circular effect, a synergy. Whether or not they involve decisions, additional steps add handling time. Having already slowed play on that axis, it can be very tempting to expand rules "horizontally", adding more variations to each step.When your options are so limited, how much time can your spend?
There is no bar to piling on situational modifiers in old D&D! That one book or another offers but few examples can be misleading if one does not understand that ad hoc adjustments are not only not "against the rules" but an assumed part of play.
However, neither is there a bar to not complicating affairs; complexity is not mandatory. Your DM will adjudicate such matters with common sense. When important single combats occur ... then details may be considered that otherwise might get glossed over.