Delays in a project can be a major factor for the failure of it. There are multiple solutions around this however. The solutions are specific to what the time delays are caused by. But in general, most unexpected delays can be solved by getting inputs from team members and collaboratively thinking of a solution. If that doesn’t work for whatever reason (maybe the team doesn’t have enough experience, etc), the team should reach out to different teams within a company or seek outside help.

Pertaining to the second question, the time for a project experiment should never be shortened for the purpose of efficiency. It is better to extend the timeline of the project and have more accurate data than to shorten it. This will ensure the success of your project in the long run. Sometimes it is better to shorten the experiment if its a repeating experiment. But the experiment should be repeated enough times to ensure that its shortening will not have an effect on the outcome.