It can often be the case that teams tire more quickly when they do a lot of chasing, especially at this level. However, we seem to train for this scenario and it allows us to remain as sharp as any other team throughout the 90 minutes, even if our ball retention isn't as good as others.
It must come as a big shock to teams, going into the latter stages of games when we seem just as fit, if not fitter, than the opposition.
Perhaps that's why we score so many late goals.