One of the things people often find a source of frustration is when they have created a change in behaviour but at some point in time old behaviours start to resurface. Behavioural science helps us describe what's actually happening.
When undesired behaviours are put on extinction and new desirable behaviours are instead reinforced, if at some point later the new behaviour is then put on extinction (is no longer reinforced by the persons environment), the old behaviour may pop back up.
This is known as resurgence.
It may sound complex but it could be as simple as a leader purposefully stopping reinforcing one set of behaviours in their team and starting to reinforce new targeted behaviours. If at some point in the future the leader gets distracted or declares victory way to soon and stops reinforcing the new behaviours, you can expect the old behaviours to pop back up again.
The strategy for avoiding resurgence is to keep paying attention and reinforcing desirable behaviour.
Another scenario known as renewal is when a behaviour is reinforced in one context and then extinguished in another and on return to the first context pops back up again. So thinking of the above example, a person is reinforced for a behaviour in context A, they then move to context B (a new manager for example) and that person reinforces different behaviour. Should they then go back to an environment similar to (but not necessarily the same as) context A you should expect to see the old behaviours come back.
This is happening because learning and behaviour are context specific.
This requires a different strategy. Never assume that because you can get desired behaviours to occur in one context, it will happen in another. Expect that the behaviours you see for example in a one to one with you versus a meeting with others, on one project versus another project, in the office versus on site, will vary, due to the change in context.
Renewal proof your behaviour change by purposefully shaping up new behaviours in multiple contexts.