Why might people stop doing X when they feel that they're under delivery pressure?

Thoughts from a discussion at Kaizen Camp Sydney 2014,

Why might people stop X, where X is a "new, better way of working", when they feel that they're under delivery pressure?

1. They don't believe X contributes to delivery
2. They have neither KPIs nor budgets allocated to X.  That is, the organisational body language is saying that X is not important.
3. They have no decision authority over whether to do X or not
4. X doesn't actually work and that's usually because...
5. They didn't actually do X so "X" doesn't actually work and that's usually because...
6. They didn't understand what X is nor what the critical parts of X are