I grease often. Anytime the tractor is out doing a day's worth of work (ie, I won't grease it if I'm just moving it out of the way). Loader, tractor, cutter etc is greased, fueled, oil checked, trans checked, toolbox checked etc. If I'm on a customer's property, I don't want or need any downtime, especially if its preventable.
My father owned an excavating business. Everything was greased when warming up for the day. No exception. We still own a 1968 Hough loader with original pins and bushings. Joints have minimal wear and slop.