Devices of this sort are generally not rated in terms of duty cycle or maximum cycles per hour, in some part because user-chosen accessories have a large influence on what is or is not feasible in an end application, and in some other part because the limitations that apply arise from entirely different reasons than those which are relevant to electromechanical relays.
One can refer to the below chart in the datasheet to get an estimation of maximum permissible load current based on which factory-qualified heatsink is chosen and ambient temperature. Note that heatsink performance is affected by a number of factors, such as airflow/mounting position, surface contamination/debris buildup, humidity and atmospheric pressure, etc. In other words, take the chart with a grain or two of salt and leave oneself some generous margin.
This post outlines the basic process for making thermal calculations in electronics applications, and can be transferred to situations of this sort with minimal inference.
To a first approximation, solid-state relays are insensitive to switching frequency and limited in their carrying capacity only by the ability of the installation to remove heat that is generated as current passes through the device. The contact arcing phenomenon which is the primary wear mechanism of conventional relays is absent in the solid-state variety, but in trade SSRs have vastly higher conduction losses that require deliberate thermal management.