"Not just a daytime band" is true at this season most years, and occasionally at other seasons as well.Much of the rest of the year, late morning to mid-afternoon works best because MUF is often not high enough in hours of darkness; but in summer, and especially with current levels of solar flux, sometimes the MUF is so high that 22 m is on the back side of the slope from the OWF/FOT point far enough to suffer excess attenuation in peak daylight hours. That effect is less notable at amateur power levels, where QRP can be 30 dB greater than the maximum radiation limit for non-licensed operation.
(One could argue that hams have become spoiled by being able to measure power in watts, and that's the reason they approach 22 m beaconing with what often seems like sloppy disregard for bandwidth, frequency stability, need for antenna omnidirectionality, etc. What's "good enough" at 200 mW to 5 W may be OK on 20 meters. But at Part 15 levels, every decibel and every Hz matters when one is working so close to the noise floor.)
Thus, evenings are often better than noon, and sometimes F-layer paths stay open all night. And sporadic-E is not just a daytime phenomenon, either, for that matter.