One of the teachings many give about AGM's is "Do Not Equalize" yet the manufacturers give instructions for equalizing on their web sites.
Fact is.. Equalize "AS NEEDED" not based on a calendar. but if the batteries seem to be loosing capacity, Give it a try. Battery type (With one exception) does not matter here.. DO NOT EQULIZE GEL CELLS (of curse 100 amp hour class Gel Cells and larger.... Kind of rare,, AGM very common, Gel, usually have amp hour ratings in the single digit range and even those have been replaced by AGM in many cases).