Here is one experience I did not maybe consider enough:

the teams that behave the closest to what the Agile manifesto seems to define as agility had three things in common, two of them were inside the team:

1. emotionally mature team members

2. competent team members that were able to deliver and knew their strenght and acknolwedge their unknowns

and the one item outside the team:

3. Trust and respect for them from the business leadership

Of course having these 3 things makes any SDLC work