“[A]n appellate court should not interfere with case management decisions by a judge who has applied the correct principles and who has taken into account matters which should be taken into account and left out of account matters which are irrelevant, unless the court is satisfied that the decision is so plainly wrong that it must be regarded as outside the generous ambit of the discretion entrusted to the judge.”
“But the burden lies on those seeking to displace its application in the particular case to make out that the ordinary rule must as of necessity be superseded by this paramount consideration. The question is by no means one which, consistently with the spirit of our jurisprudence, can be dealt with the by the judge as resting in his mere discretion as to what is expedient. The latter must treat it as one of principle, and as of turning, not on convenience, but on necessity.”