Is the timebar app supposed to sync multiple cameras perfectly?

I bought the Sync E to connect to one camera that doesnt have video in/out metadata so I could combine it with my 2 GoPro Cameras for multi camera recording.    What I am finding is that using the timebar app I can sync to my Sync E camera and also with a QR code get my 2 gopro cameras in sync.   But in post, I am seeing drifts back and forth of upto a second between clips. Varying drift and not something I can easily drag everything over to account for latency.

Is this what is expected from this device and app?  It might not even be a tentacle sync issue here if it turns out that is just how gopro’s internal clocks run.

For *fun* I tested a 3.5mm splitter to run my one Sync E to all 3 cameras.. but when I tested that results were inconsistent – the windows timecode tool wouldnt recognize the audio TC intermittently even though it was clear in the left channel with no distortion or mixing of channels.