Techstream EGR Valve Blockage Data

Mine runs every time I drive it. It is not too picky and the values have been high for years. The sensor is not laboratory grade; the value can change from 20-22 from one test to the next.

 

Before I cleaned mine it was showing 10 point something. 21 or 22 after cleaning.

My before-cleaning situation was both a gunky cooler and a rutted ski-jump in the valve.

 

The 20+ kPa you're getting means your system is not clogged. That's not unusual, even for systems that have not had the cooler cleaned. My car's, for example.
Of course values after cleaning are higher than before cleaning. That just means the cleaning was successful.
Toyota does define a minimum "good" number below which one should clean out the EGR tract. It's reported with the test result, like the 0.87 kPa (not PSI!) in rjparker's example above. However, many consider that value too low. You could arbitrarily choose 10 kPa as a more conservative safe limit.

 

Or, if you saw that 10 was a reading I had when suffering from both a somewhat gunked-up cooler and a rutted ski jump, you could decide you'd rather not wait as long as I did, and set a target number somewhere above 10 kPa and lower than 20.

So far, we have plenty of data on what "pretty good" numbers look like, but haven't really established a basis for any particular number to be the threshold where you want to do the work.