One of the techniques to save fees is doing consolidations. According to https://en.bitcoin.it/wiki/Techniques_to_reduce_transaction_fees: "if your usual target feerate during normal-priced fee periods is 100 nanobitcoins per vbyte and the current feerate is 10 nanobitcoins per vbyte, you could save up to almost 90% on fees by consolidating now before you next need to spend some of those inputs."
However, this is under the assumption that your coin selection strategy will only spend low value UTXO at a high fee rate (which isn't optimal to begin with).
It seems hard to measure the the cost savings because it's hard to predict when the UTXO would have been spent in the future. One way to measure the "savings" is by comparing spending the UTXOs at the time of consolidation vs at the time of spending the consolidation transaction. One can measure if the consolidation transaction was profitable. However, this metric seems misleading because those same UTXO's could have been spent sometime later under a different fee rate.
Is it impossible to have an accurate measurement of fee savings from doing consolidation transactions?