Lots of solid replies... gonna depend on your specific terrain. I am on slopes 90% of the time and off hard pavement so my default is 4x4 engaged. If I go onto hard surface I disengage... go off road I engage. Makes life simpler and safer.
Your Kubota will be the only newer model I've ever saw without an indicator if it doen't have one. Mine is a small green tractor shaped light in the dash pod. Similar in size to the PTO indicator.
Define newer please?
Ours is a 2011, and the only indicator is the 2WD-4WD lever to the right of the seat.
On a really big honking full-size Ag tractor, it would make sense to have an idiot light for it, but on our little CUT, it'd likely be overkill.
Similarly- where we don't have hills, we have swamp, and very little in between- none which we particularly care about scuffing up a little, so we take 4WD off as we head into the barn to park it, and re-engage it when it has pulled off the pavement and onto the gravel driveway/parking pad.
Also, we always disengage for the [very rare] episodes of road travel.
Last Fall I bought a JD 3038e I really like, but how/when do you use 4x4? Sounds like a stupid question, but I forget and leave it in 4wd a lot. I was bushhogging just now in 2wd, but hilly parts and it started to rain I had to put it in 4x4. I guess my point is does it hurt to leave it in 4x4 or better not to. Thanks!
Only when needed. Saves fuel and wear and tear especially tires.
In hilly terrain, if you want to be safe, ALWAYS leave it in 4wd. Otherwise, you'll have no brakes when going downhill.
Ralph
Actually the answer is simple.
Only when rear differential lock fails to do the job.