No, fortunately the guesses described above are not how zigbee mesh works. If it did it would not be at all suitable for home automation deployments.
You can feel comfortable that as long as you have done at least one zigbee heal since all the devices were first added the arrival sensor will use the best available path. No matter how many repeaters you have. 
The issue of the arrival sensor getting confused and thinking you left is an entirely different issue. Sometimes itās a platform issue. Quite often itās interference from boosted Wi-Fi. (I have this problem with my own home. The arrival sensor will work fine for much of the day, but on many days right around 330 pm it starts bouncing back-and-forth. I suspect one of my neighbors has boosted Wi-Fi and a teenager gets home from school around that time.)
Support may be able to help, there are a few things they can do on their side. Additional zigbee repeaters can only help, not hurt. But sometimes the set up at one particular location just doesnāt work with the arrival sensor, and then you have to look for alternative methods for Geopresence.