Budget 1 vs Budget 2

As much as I want to support the budget committee's recommendation, I'm leaning toward the petitioner's budget this time around.  I agree that having more reserves is a good thing for the town in terms of credit ratings, etc.  I also agree that a rainy day fund is a good thing.  However, if the charter specifies a percentage of reserves, shouldn't we adhere to that percentage + or - a small variance?  If we should have higher reserves why don't we change the required percentage in the charter?