The US tax system is a pay-as-you-go system. There is nothing wrong with claiming as many allowances as needed to avoid a large tax refund as long as it does not result in a significant balance due. The problem would be claiming an excessive number allowances resulting in your tax withholding being insufficient to reasonably cover your per-quarter tax liability for the year. Claiming the appropriate number of allowances does not mean that you are giving Uncle Sam an interest-free loan, it means that you are simply paying on time and that Uncle Sam is not giving you an interest-free loan.
