I really don't think that it makes sense to always go for the 2%. If you are using 1% and have a healthy scalp condition - why bother with 2%.
There's the cost factor, but also the increased chemical load. Usually the lease effective dose is also the most effective, though individually determined. The benefits of a particular treatment at a particular dosage are not necessarily linear, i.e. sometimes less is more (or at least the same).