Having a dedicated team is definitely important. I had a similar experience to yours and I am not entirely sure why. I think a big part of it is that once you

Having a dedicated team is definitely important. I had a similar experience to yours and I am not entirely sure why. I think a big part of it is that once you dig into complexity points and time estimates and all that other stuff, people tend to be on the safe side and add a lot of buffer. But when the whole team is in the hacking mentality and just wants to get sh*t done, you don't need to have everything in sprints. You just need a highly motivated and a dedicated team.