Why is it better to use a micropipette that can transfer 200 microlitres or less, to transfer 200 microlitres, over using a pipette that can transfer 200 microlitres or more?

RULE OF THUMB: Always select the SMALLEST size pipet that will handle the volume you wish to move to achieve the greatest accuracy. Accuracy decreases as you use unnecessarily large pipets for small volumes. With the smallest pipets, you have much better thumb control on rate of discharge.