Any subsequent update will always be more accurate than the previous update. Also you dont need the update to propagate through the entire network for it to be useful. Every new node that receives it along the way creates a higher percentage of the network using the new parameters.

In any case, the use case in my head is more for adjusting rates on wildy fluctuating channels (not for making minor adjustments). For instance consider you open a channel to a sink and they suck all the liquidity to their side straight away, so theres no more routing capacity in that direction. You'll want a fast and severe increase in fees on that channel to prevent any more nodes from trying to send funds that way. So in that way it helps the network at large because there should be less failed attempts to route payments.

With the current LND autoloop, you'd be waiting 3 days for an update and it would only be a percentage of the median change in liquidity across all your channels (or something like that, i cant remember it exactly of the top of my head). So meaningful change on a completely exhausted channel will likely take several cycles of fee adjustments.

Does any of that make sense?