Regulating the Aftertouch is definitely a touchy-feely operation!
The depth of touch is just a basic setting. The touch depth block is just a guide. The actual and ultimate setting is determined by the FEEL of the jack releasing from the roller (the hammer releasing from the key): this is the AFTERTOUCH. Super-thin paper washers (factors of 0.01 mm) make all the difference to evenness (regulation) of this setting from key to key.