This bunching problem runs deeper.
IMO its two fundamental issues:
1. Poor runtime planning, some overly long some overly
tight.
2. Poor ability of BC to pace himself. Some F1, some like
snail.
Both need each other to be fixed to reduce bunching.
As a footnote, no amount of monitoring, fines, rewards or
surveying will solve this problem. Proper planning, training and
subjecting both bus captains and runtime planners to being
accountable for their poor performance, will.
Don't forget en-route conditions also...