How should slump tests and test cylinder records be handled at a concrete pouring site?

If you pour concrete on-site based solely on the driver's delivery ticket, the risk is very high. We previously encountered a situation where water was added to a truckload, causing the slump to exceed limits, and the dispute only started after the strength report came back. My process is to first verify the delivery ticket: mix design, design strength, departure time, truck number, and arrival…