I haven’t really looked into it yet, and I’m not entirely sure how to measure it accurately?
Even a very basic hygrometer will give you enough of the essentials to get a handle on what's going on, and if the DnD machine is new enough, it ought to have sensors telling you what's going on in the drier (the industry standard manual that covers the fundamentals of process machine design has an extensive section on drier design, drying faults and how to prevent them).
Unless you have an impingement (or equivalent) drier on the machine, you generally want to ensure your drying time is really not less than 15 minutes, but if your ambient/ drying unit humidity level is low, the temperature you specified using may be way more than you need to hit that aim (in fact you may need no heat at all if your relative humidity is low), and thus you are potentially drying in spots and shoreline marks etc.