All I know is, when I bought the used open station M9, it was so caked with old grease (least the previous owner greased it) and mud up under the undercarriage (in places I have to wonder how it got there), it took me 4 pressure washings to get it all and that's with all the tin off the tractor too.
When I pressure wash, I use a wider fan nozzle so as not to drive the water into places it shouldn't be and I use purple ZEP or Purple Power degreaser (straight ) to help with the grease and grime removal and I always re grease after washing.
I really don't like touching any part on equipment of any kind and coming away with filthy hands because the filth gets transferred to other things that don't need it transferred to like a steering wheel for an example, or a seat (I have a rather expensive Grammer cloth, air ride seat in my cab tractor,) don't need grease on it....
One thing I never pressure wash my hay tools, especially the round and square baler. I wash the outside sheet metal with the wide spay maybe once a year before I pout it away but they always get blown off with high pressure air. hay chaff don't turn to grime like grime dies anyway, Way too many bearings and chains on balers that can get compromised with pressurized water. I know, been there with a bearing on a round baler and it was an expensive fix, live and learn I guess.
Far as I'm concerned, there is no plausible excuse for not keeping equipment clean and grime free other than being lazy. JMO.