Ideally we’d deliver work fast and on time, but there are just too many things that get in the way. Itès best to learn how to do it on time before we learn to do it faster: consistency and reliability are more important than speed.
'Faster' means controlling what slows us down, which is unlikely if it involves other people or external constraints.
'On time' means understanding what the external constraints are and working them into our schedule: it's a lot easier than you think.
Clients will be extatic that we can deliver so quickly, they will take our promise to deliver on time to their stakeholders who will organize themselves and others and make promises on our behalf. Failing to deliver on time will mean letting down a lot of people - and no one will remember the quality of our work, just that we let them down.
On the other hand, clients may not be happy to hear the amount of time we need to deliver the work, but they can make arrangements around this.
Building a reputation of delivering when we say and they won't mind if it takes us a little longer than others. And then we can work to become faster.