The critical thing here is the "solstice point" which is the brief instant when the axis of the earth is in the plane defined by the three points 1.) center of the earth, 2.) center of the sun, and 3. a pole of the earth.
Since everything's in motion, the "day" preceding and "day" following, or the night preceding and night following, can be exactly equal only for persons at a longitude that lies in that plane exactly at the instant of the alignment exactly at midnight (or noon), so one day/night is always "just a bit" longer or shorter than the one on the other side of that "instant of alignment" for most of us.
For ritual purposes of frolicking naked in the vinyards it hardly matters if one misses by a day, but to be safe celebrations on the two consecutive nights might be advisable if there's any doubt.
It should also be noted that the 365.2422 days per year refers to the "solar rate" of rotation of the earth, but if you're navigating by precision inertial references it's necessary to use the "sidereal rate" and account for the fact that the earth actually rotates through 366.2422 rotations relative to the galaxy during one 365.3422 day year. Puzzle that one out if you're so inclined.