During the course of a deposition there is no judge present to rule on objections. Attorneys may make objections during the course of the deposition but the general rule is that the only objections that need to be stated on the record are those objections that go to the form of the question. These types of objections relate to defects in the way the question is worded which could be cured by the other attorney simply by rewording the question.
Depositions in general are used to discover what parties and witnesses know about the facts of the case so as to allow the attorneys to streamline their case for presentation at trial. Some courts do limit the number of depositions that may be taken by either side so as to prevent one party from abusing the process.
Some courts also impose limits on the length of depositions i.e. six hours. Depositions can become very contentious on occasion. If that is the case then it may become necessary to seek the involvement of a local judge by phone to get a ruling on the objections of one party or the behavior of one attorney.
Once a deposition has been taken then it may be used at trial under certain circumstances by reading it to the jury/judge or may be used to contradict the witness if the witness gives contrary testimony at trial.