Expand frequency discussion

Author: tfpauly

draft-edm-protocol-greasing.md

@@ -205,8 +205,23 @@ can be made unpredictable. Implementations can vary their behavior by including
 no grease values, one grease value, or multiple grease values for a given protocol
 extension point.
 
-TODO: Discuss the implications of how often grease values are used; using very
-infrequently and very frequently can both be ossifying
+How consistently an frequently to use grease values is a choice that implementations
+and deployments need to consider and weigh against several factors.
+
+Deployments of greasing should consider how they expect errors exposed by
+using grease values to be noticed and measured.
+
+If grease values are sent too infrequently, so that errors due to sending
+grease values blend in with the noise of other errors, it is likely that
+no one will notice failures, thus defeating the purpose of greasing.
+When grease values are sent more frequently, they will be noticed more.
+However, if grease values are sent too consistently, receiver implementations
+might end up special-casing grease values.
+
+The patterns for sending grease values can be made more effective by
+coordinating between devices sending the values. One example of coordination
+is having a "flag day" where implementations start sending grease values
+broadly, and measure to see where errors occur.
 
 ## Don't Handle Grease Values as a Special Case