How many hours do you have on that tractor?
Having done countless valve adjustments on my motorcycles, I have seen that (at least on those engines) the clearances will close up over time. It looks like the BX engine has a screw/locknut arrangement, as opposed to the shim under bucket. That makes this a MUCH easier ordeal.
If your engine is truly up to the hours that call for an adjustment, I say go for it. Make sure the engine is cold. Remove the valve cover. Check the lash as described in the manual, and first see if any are out of spec. If they are, it's a simple adjustment. Loosen the locknut, turn the screw, re-tighten the locknut.
The last thing I would recommend is before putting it all back together, roll the engine over a few times and then make one final check with the feeler gauges. On my bikes anyway, I have found that from time to time, and for whatever strange reason, a final adjustment is needed.
As far as "if it aint broke don't fix it," that does not apply to maintenance. As the valve lash closes up, the lifters get QUIETER, not louder. There is a reason that this operation is on the maintenance schedule. When the clearance disappears, the valve tulip no longer contacts the seat, and therefore will not cool. It will then burn up. I have also seen this on my beloved Bavarian motorcycles.