Yes, in most cases of tropo, that is the pattern. The high sun often raises the temperature at all levels and you may lose the duct for a while. However, as pointed out above, there are plenty of exceptions to this. I'll give another. Quite a few times, I've experienced ducting that brings FM signals from western Michigan (Grand Rapids, Holland, Muskegon, Kalamazoo, Benton Harbor, etc.) into Chicago's N and NW suburbs. Those signals travel from their home markets, across more than 60 miles of Lake Michigan, then over a few more miles of land to get here. The tropospheric ducts which enable them to make that journey are formed over the lake - and are associated with the difference between the lake temperature and that of the air above. During the spring, the lake is cold and the overlying air is warm - but lower layers are cooled by the lake. The inversion is actually strongest during the afternoon hours. So, I've noticed tropo that is at its best around 2 or 3 pm and which fades by 6 pm.
In other words, unlike what happens when AM signals bounce off layers in the ionosphere at night, there's no hard and fast rule about tropo. Though it's most common early in the morning and later at night (when relative humidity is highest), there are plenty of exceptions to this and the reason for the phenomena has less to do with whether there's daylight and more to do with specific atmospheric conditions.
