Typically how long after the plaintiff's lawyer conducts a deposition , does the defendants lawyer conduct a deposition ?

Plaintiff's lawyer conducts a deposition on the defendant. Does the defendants lawyer a). Wait until the transcripts from that deposition are populated before he conducts his deposition b). Conduct his deposition shortly thereafter ( days) c). wait several months to conduct a deposition to prolong a potential trial date d). Not request a deposition of the plaintiff at all and if so is there a time limit to request a deposition? e). Other....Also is there a disadvantage of not requesting a deposition?