First off, like once every month or so, get it out and run it getting everything up to temperature, run your PTO, run your 3 pt up and down, run your FEL if you have one up and down limit to limit.
Recommendations are a crap shoot since who knows what kind of service each buyer will put their tractor through. I use some common sense and adjust accordingly. On seldom used items, I run out the time schedule but pretty much adhere to the hours recommended. Right now, being retired, I probably run most of my fleet at 100 hrs. Oil changes are on a 2 year cycle or recommended hours, which ever comes first.
The 3910 I just bought is 30 years old. 900 hrs makes for 30 hours per year on the average. Not much usage. In changing the fluids I noticed about a quarter inch of sludge in the bottom of the engine oil pan. Detergent oil is designed to keep particles in suspension and if engine is used frequently and oil changed somewhat reasonably they will remain there.
However, if dirty oil sits for a long time, gravity will put those contaminants at the bottom of the container and what used to be black oil will look more like honey....BTDT with a closed, clear, plastic drain pan, full of dirty engine oil, I had sitting on a shelf and forgot about it for a year or so. By cycling your functions as mentioned you will keep everything lubed and dirt in suspension.