We use the same primary tubing for all units of blood hung in a 24 hour period. We do change the secondary filter with each unit that is hung. This has been a recent change to our policy. Prior to that, we hung two units per tubing.
Prior to the introduction of IV contol devices, we had to calculate drip factors and manually set them using the roller clamp. At that time 20 cc/hr was considered kvo rate. (much easier to calculate) At the hospital I work at, all fluids are on pumps and these devices provide constant pressure that permits fluid rates as low as 5cc/hr without problems. I'm not sure if this is the answer you were looking for.
At the hospital I work at we will be treated to dry cake and coffee. However, my immediate supervisor just took all of us out to a 5 coorifice Italian dinner, which was fabulous. I also got a $25.00 gas card and $10.00 Bath and Body works certificate. As I have said before, MY BOSS IS THE GREATEST!!!!!!!