You are partially correct on the "eyeballing".

When I make the first cut, I use soap stone to mark the end of the cut and make the first cut. If the blade did not hit the mark, or is short of the mark, I readjust the the blade depth with the original blade stop that came with the saw. Make additional cuts until until the blade hits both centers.

For the second cut, roll the pipe and pull the pipe up to the blade where the second cut will be made. Now "eyeball" to see if first cut is parallel to the table. If you are close, make the second cut.

If the cut piece just falls out you're good to go. If the cut is incomplete, roll the pipe with the blade down to cut the remaining piece. At this point you can make a stop to index the the first cut and you will be able to repeat cuts as quickly as you can handle the pipe.

The training time is minimal, after my 3rd pipe was cut, I was able to "eyeball' the set point for the second cut. Be sure that the blade is properly set.