You can't predict, you can't prepare
Howard Marks, The Most Important Thing: Uncommon Sense for the Thoughtful Investor
As a product manager, I love reading books on investing. There are a lot of similarities between financial markets and building products. Say you're planning a new feature to be built. As a PM you need to assess whether the price of this feature represents its value adequately. Even better if you can make the perceived value in the eyes of your customers much higher than the price you charge for it. Quite the same in investing, when you're analysing the market and need to make a buy, hold or sell call. In both places, you deal with incomplete information and other players. So the risks are never zero.
In investing, Howard Marks says, you can't predict and you can't prepare. The market always has a way to surprise even the most sophisticated investor. But how about product management?
You can predict and prepare
Delivery schedule
Predicting when a product will be completed is tricky but definitely possible. All you need is an experienced team who have done similar work before, a known fixed scope and quality parameters. You might not be right to the day with your prediction as things could happen outside your control but in general, you can know when something could be delivered.
If you want to be thorough, you can also prepare for different eventualities. For example, you can estimate a few possible delivery dates and then prepare different communication depending on which date finally comes through. Or you can prepare a scope reduction if, in the process of building the product, you'll see major delays.
You can do a lot with the delivery schedule. However, one thing you cannot do is bend reality. Often people would forget that and try to push for miracles. They would keep the scope and quality fixed but demand major gains in schedule. Inevitably these attempts always fail and often a product manager is being made a scapegoat. But it's not a product manager, it's just reality.
Quality
Another aspect of your product you can predict - its quality. And it's not too complicated either. The number of tests you're having, how many people tried your product before the release, did you used best practices while building it.
Despite quality being so straightforward on paper, in reality, so many product releases disappoint especially in the quality aspect. The reason might be again in attempts to bend reality. In order to increase scope or shorten the time to release managers would compromise on quality and try to hide it. Don't be such a manager as it will come back to bite you.
Scope
This is something a product manager should be able to predict as they are the ones who set it. Only product managers who can say "no" control the scope of their products. If anyone else can add (and it almost always adding) to the scope, then sadly you're no longer a product manager. However, if PMs can control the scope of their products, they also need to know their team and what it is capable of. You can't predict building products with people who you don't know well.
If a product manager is not in control of the scope then they at least can prepare for the inevitable consequences of compromising on either quality or delivery schedule.
You can't predict and prepare
Value perceived by customers
Even though the main responsibility of a product manager is to provide value for customers and their business, PM cannot guarantee that the value will be perceived by customers. Yes, if the PM does their homework - product discovery, prototyping, testing, MVPs... that kind of unrealised value could be minimised but cannot be fully eliminated.
As a PM, you can try to be prepared for surprises. You can envision several product changes if the initial version didn't bring the results you were hoping for. Still, it's important to remember - success is never guaranteed and this is what makes the product manager job fun.
Virality
Another aspect of any product that cannot be planned for - is virality. When something goes viral it's always due to a lucky chance. Not fully of course, You can design your product for virality and can do a thousand small things to make a lot of people engage with your product. Still, it's impossible to predict virality.
And similarly, it's hard to prepare for virality. When it happens you can be blown away by the effects and not be able to cope. Plus when something goes viral it often changes, and almost starts to live its own life. This is something very hard to predict and prepare for.
Macroeconomic shifts
Product managers should not forget our products exist in the bigger world where major changes are not only possible but pretty often. Sometimes, the success or failure of our products is completely outside of our control. Major events or trends might decide the fate of our products and we cannot do much about that. We can't predict when, how it happens and for how long. Maybe we can try and prepare some backup plans, and emergency funds to extend our runway. Yet at times, the market forces are just too great for us to do something about.Why does this even matter?
I've seen and worked with so many product managers from very different backgrounds and experiences. What I noticed is the most grounded, the most self-aware product managers are the ones who tend to be the most content and satisfied about their jobs.
In other words, those PMs who know what they can predict or prepare for get better results both for themselves and their products. And for things they cannot predict or control - they remain calm and stoic, saving their energy and nerves for battles to come.