When I've charged for consulting work the smallest unit I've allocated to a client is half a day. That means I work for one client before lunch, and potentially another after, both get charged 4 hours (or 3 hours when I did 6 hour days).
If I finish my assigned task within 10 minutes, then I find something else to do for that client to fill up the rest of the time. It usually leads to them being pleasantly surprised at me taking lead on improvements, and gives me a chance to refactor things that are difficult to maintain.
If I finish my assigned task within 10 minutes, then I find something else to do for that client to fill up the rest of the time. It usually leads to them being pleasantly surprised at me taking lead on improvements, and gives me a chance to refactor things that are difficult to maintain.