I heard before that generally speaking you want max tracking force allowed and minimum bias to get the best sound.
Max tracking force has never been my recommendation (unless you're a vinyl newbie - and I know you're not, Inna). Newbies are well advised to play their cart near the top of its VTF range, as this minimizes the risk of mis-tracking and vinyl damage. Experienced listeners are capable of extracting better performance by playing with this adjustment and all others.
Sonically, my cart performs best with the MINIMUM tracking force and A/S that are compatible with clean tracking. Increasing either adjustment beyond that point diminishes performance.
This is because downforce and A/S both use the tonearm to apply pressure to the cantilever and suspension. Whether that pressure is vertical or lateral, damping and slowing of dynamics results.
The ideal settings certainly do vary from record-to-record, even groove to groove. Perfectly unsurprising, as you said. It would be astonishing if this were not so, or perhaps just indicative of a less capable system or listener.