In this initial question, focusing only on the costs of the expert would certainly be "short-sighted"! What is crucial instead is how much security the client wants. With only one (here hypothetically assumed) site visit, the probability that the targeted safety goal will be achieved approaches ZERO. In other words: then the visit could just as well be omitted. Decisive in purely technical terms (and this must have priority) is the question: how many critical construction phases make the use of occasional construction supervision necessary? This question is particularly justified in another respect since in Germany most construction projects are raised without control by the client – and it still works! What could prove to be critical in a process, i.e., where a "need for control" exists, can only be decided by the expert with his experience and professional competence. If this question is answered exclusively by the wallet, uncertainty arises elsewhere, which competent control appointments are meant to prevent! Regards: KlaRa