I recently went over a year without recalibrating, which had both positive and negative consequences. I never felt like taking the time every month when the reminder popped up - I rarely saw any noticeable difference afterwards, and it randomly seemed to miscalibrate every so often, which is why I suggested running it a few times to see if you get anything different. I found 2 major things that were off when I finally recalibrated - the contrast and saturation were much higher after recalibrating, and apparently I hadn't noticed that my display had been set to "automatically adjust brightness" after a system update, resulting in a much darker image.
This meant that for a long time my display lacked contrast and saturation and was too dark, so I was really boosting the contrast and vibrance when editing, as well as brightening my images quite a bit. Interestingly, I actually liked how my images were turning out, and with few exceptions, looked great on other devices such as iPhones or iPads. Of course now everything on this display seems too bright since I got used to it automatically dimming, but it has actually changed how I edit.