I have been wiring my house with ethernet cables, and was testing the connections with a simple ethernet tester: you plug two cable ends into the tester, and it tells you if the cable ends are connected to each other and the 8 wires are in the correct order.
Let's say you have unlimited patch cables which are known good, and you want to verify that all wiring has been done as intended. You also want to do it without walking between buildings any more than is necessary.
The wiring is between two buildings, A and B, and there are 6 lines to test, 6 ports in one building, and 6 ports in the other: A(1-6) and B(1-6). All lines are wired from one building to the other: line 1 connects port A1 to port B1, line 2 connects A2 to B2, and so on.
For example, you could patch A1 and A2 together and go to building B to test that B1-B2 are connected as expected. However, this is not enough to prove that lines 1 and 2 are wired correctly, because if the connections cross, (B1-A2-patch-A1-B2) you'd get a false positive.
What's the minimal number of trips between buildings you have to do to make sure that all the wiring works, and every line is connected as expected?