I think the correct strategy is to always spend from the UTXO with the highest amount of bitcoin. Is there is a flaw in this strategy?
Well, if you have many UTXO and also spend a lot, sooner or later you can easily end up with small inputs off this, so you still have to consolidate now ant then.
The strategy is not very bad, but not the best either. However, I feel that the problem of small inputs is coming more from how you earn/get to your custody those UTXO (so you may not be in real danger).
Since I have - now and then - to convert Bitcoin into fiat (sadly), one strategy I take is that when I have to spend I pick some 1-2 UTXO with the sum not that far from the amount I need, and the change I send to the centralized wallet that I use to convert to fiat (not nice, but meh).
Yeah, I plan on consolidating once fees are lower. Just thinking about ways to reduce the amount of potential dust.