This summary is not the rule. The rule text controls.
Most deadlines mentioned in these disciplinary rules are meant to keep things moving smoothly, not to control whether a case can go forward. If someone misses one of these regular deadlines, it does not mean the case gets thrown out or stopped. The process can still continue.
However, two types of deadlines are treated differently and much more strictly: deadlines for filing an appeal and deadlines for asking to be reinstated to practice law. These deadlines actually control whether the case or request can move forward at all. If you miss one of these, you could lose your chance to appeal or to seek reinstatement.
If someone misses one of the regular, less strict deadlines, they could still face consequences, like being held in contempt by the disciplinary agency handling the matter. But missing these ordinary deadlines will not stop or cancel an investigation or disciplinary case already underway. In short, most deadlines keep things organized, but the appeal and reinstatement deadlines are the ones that really matter for whether your case can proceed.