Your editor realized one day late that she had neglected to serve the expert witness demand. She called opposing counsel, who had also missed the deadline to serve the demand. They stipulated, which was confirmed in writing, to exchange demands that same day, and that the demand would be deemed timely served…
In another case, an attorney refused to grant an extension for the other party to respond to discovery, threatening to seek issue preclusion and terminating sanctions … when that attorney later needed an extension to respond to a motion for summary judgment, the request was denied.
As a corollary to the above rule, attorneys and judges have a long memory and the legal community is a small community. The other attorneys in the courtroom, and the judge, will remember that you were apparently clueless about the case or arguments to be made, misrepresented the facts, reneged on an agreement, or insulted your opposing counsel …