"In preparing for battle, I have always found that plans are useless but planning is indispensable."
"I tell this story to illustrate the truth of the statement I heard long ago in the Army: Plans are worthless, but planning is everything. There is a very great distinction because when you are planning for an emergency you must start with this one thing: the very definition of "emergency" is that it is unexpected, therefore it is not going to happen the way you are planning."
These are two Eisenhower quotes, and they point at one of the most important things in the conduct of military operations and they preparation for warfare by the officer corps.
It is of great importance to have red teaming (trying to figure pout possible hostile actions) and to understand the terrain, forces and especially the possible routes and their characteristics. It's very useful to calculate in advance whether something may possibly work out well.
What's not essential is the detailed plan, for
"The tactical result of an engagement forms the base for new strategic decisions because victory or defeat in a battle changes the situation to such a degree that no human acumen is able to see beyond the first battle. In this sense one should understand Napoleon's saying: "I have never had a plan of operations." Therefore no plan of operations extends with any certainty beyond the first contact with the main hostile force."
That was Moltke the Elder speaking.
I think these insights should guide what to expect from campaigns, how to design staffs from (manoeuvre) battalion to theatre level, doctrine and training of staff officers and COs in general.
The biggest challenge is probably not how to say or write a sufficiently concise order, but how to transfer the insights gained from meticulous planning to the actual leaders.
Imagine officers looking at three possible routes. They learn there's swampy terrain left and right of the road, another route has Central European noise emissions walls left and right and the third one has woodland left and right - visible on a map and seemingly indicating an obstacle there, but actually the woodland allows even heavy lorries to pass. A quick look might have made the 3rd route look worst, when in reality it's the one that's ceteris paribus the best one. That insight is a result of the planning, but how to communicate it best among hundreds of other things is not trivial at all, particularly if there's only 30 minutes for a briefing about 50 different insights.
Planning should also include a coordination of callsigns, map updates, radio frequencies et cetera - things that commanding officers don't necessarily need to know about and thus I suppose they shouldn't be so much part of an order to the CO as simply included in orders directly given to his staff. No CO reads stuff that's not relevant to him when he or she is in a hurry.
I've read doctrines of several countries' land forces on how to do staff work and orders* and I've never seen any such doctrine guided by the insight that planning is important, while plans don't last long and thus don't mean much. Nor have I seen much emphasis on letting manoeuvre forces commanders react to developments quickly and by being on the spot themselves.** It was often written in old (1920's to 1950's) German writings on the subject, but the attitude seems to have shifted hugely after decades of peace in Europe and bombardment of infantry-centric or otherwise low quality Third World ground forces.
There seems to be an exaggerated belief in plans - maybe because real warfare didn't quite challenge this belief. It might do so in the future, though.
*: Honestly; I read none from page one to last page.
**: I have seen much lip service that was crowded out by undue emphasis on the topic of plans..