Whatever the offence is, not just drink driving, the police have 6 months to commence proceedings. They are not going to reduce that just for drink driving involving a blood sample.
Some people have said how glad they were to continue driving pending conviction for various personal reasons,so for every person stressed by the wait, there are others who feel the opposite.
That is why the court are not going to give a discount on the ban because you have been waiting. How will they know which drivers are upset by the delay and which drivers are pleased?
The laboratory test the sample to be sure it is viable and if it fails their test then they will reject it. The lab is independent of the police.