Be careful what you wish for. This morning you just learned that you were incredibly persuasive in arguing that the defendants have been delaying your case. The judge has denied the defendant's motion for protective order, which is great. But at the same time she has ordered that ALL depositions be completed in the next 30 days. Not so great because you have ten depositions to take. There go your next four weekends.
So what to do? Many lawyers will figure out who they are deposing first, sit down and start preparing an outline and assembling documents for that witness. When that deposition is finished, prepare the next outline, etc. Wash, Rinse, Repeat.
Remember that each witness tells their own version of events. The key is that, in the end, you are composing testimony from several witnesses to tell a story. This is true for summary judgment motions or for trial. So in the end your goal should be to figure out how the judge or jury will perceive the witnesses' testimony as a whole. This means that, instead of dismantling each witness individually, all you need to do is show that your opponent's overall story is inconsistent or unbelievable.
Resist the urge to prepare for your witnesses individually as your first step. When you focus on the witness as a microcosm then the tendency is to spend a lot of time on what that witness did or did not do. You flyspeck their emails, make timelines of their actions, and look for holes in their story. This approach may be beneficial, but often it causes lawyers to miss the bigger picture. And when you look at the bigger picture it often changes your deposition strategy dramatically. Usually this change makes your life easier.
Let's use an example (or in 1L speak a "hypo"). Suppose that you are trying to prove the exact date that a shipment of goods was delivered. Your position is that the goods were delivered before April 1st. The opposing party argues that the goods were delivered after that critical date. The opposing party has two witnesses, both of whom agree the shipment was made after the deadline. But in your document discovery you see that in writing they noted different dates that the shipment actually occurred. One says in his notes that the goods arrived on April 2, while the other has an email purporting to document receipt of the items on April 4. One approach would be to try to attack each witness head on and make them admit that their recollection and notes are wrong. After all, if it was April 2 or April 4 you lose either way. But a simpler approach would be to encourage each of the opposing party's witnesses to entrench themselves in the date they previously stated. After all it is easier to get a witness to agree with something they have previously said.
But how would this approach be helpful? It seems you've simply encouraged two witnesses to confirm that the delivery date was after April 1. But in fact you've called into question the credibility of both witnesses. Both witnesses cannot be correct on when the delivery occurred. And since both witnesses are friendly to your opponent they certainly don't have an incentive to contradict each other. The mere fact that the opposing party's witnesses cannot agree on the critical date will cause the finder of fact to question each witness. Remember it is the overall story that needs to be believable. If the opposing party's witnesses do not present a consistent story then the finder of fact will be hard pressed to accept the overall story.
But why is this approach better?
Assume in our example that you could have argued with each witness in the deposition. You could have presented conflicting documentation on the delivery date, you could have attempted to get the witness to admit doubt or uncertainty, and you could have attacked their motives or biases. But think about how that approach would have worked. First, it would clearly have taken a lot longer. You can usually get a witness to reaffirm a position they have previously taken with a single question and answer. Fighting with them on a critical date might take hours of your time. Second, you probably would not have gotten an outright admission. How often do opposing witnesses simply roll over and agree with you on a key fact? (Very) Rarely. Third, you will have alerted opposing counsel to the fact that this date is important and that his witnesses have documented different dates. After the first deposition in which you slug out the date issue it is much more likely that future opposing witnesses will have been prepped and present a consistent story on the delivery date. They also will have ready answers for any apparent discrepancies in their documentation.
Now think about your summary judgment motion. Whether or not you argued in favor of your version of events in the depositions, you will, of course, present in your brief the arguments and evidence in favor of your date (April 1). Are you better off presenting deposition testimony where you are arguing with the witness over your version of events? Or are you better off comparing your consistent version of events to the opposing party who has witnesses each who recall different dates? The answer should be obvious.
So when you prepare for depositions think first about the potential inconsistencies between witnesses and how you can use those inconsistencies to your advantage. When you look at each witness in this light it can greatly simplify your line of questions because you no longer have to attack each witness on each fact. It will make your questioning easier and it will open up your opponent to a vulnerability that otherwise would not be exposed.