I'm just doing convergence for the first time on a Neotec 26" and it is proving not that bad.
It's taking me a lot more than 2 hours though

Needs a lot of research & thought on how the pairs of multi-pole magnet rings work. After that it makes a bit more sense. Otherwise your convergence adjustments will be little more than guesswork.
Most monitor yokes have three pairs of purity rings separated by slight gaps. Each pair is adjusted together to control a magnetic field. Each mag field influences the RGB beams in diferent ways. The combined mag field from all the paired rings is your final CRT colour adjustment.
You need to understand the paired mutli-pole magnet rings aspect before diving in and fiddling.
It does not work like pots, eg "this ring for red". I found that it made more sense after researching the theory a bit more first.
You also need some time and lots n lots of
patience. I've nearly given up more times than I can count, but instead I walked away to take a break and came back later. Yeah, needs lots of patience

Try reading this wonderful CRT FAQ, especially
s4.18 - Principles of purity and convergence adjustmenthttp://www.eio.com/repairfaq/REPAIR/F_crtfaq.html