Today, I answered your question:
 
“What are the common business strategy mistakes?”
 
Four common mistakes I have come across in businesses formulating strategies are:

• thinking a strategy is a To Do list, or a list of goals or objectives. Rather than a carefully planned, scheduled, accountable action plan with progress measures in place that takes into account many aspects of the business such as resources, processes, and capabilities.
• not correctly diagnosing the problem/situation so the strategy is ineffective.
• taking into account relevant guiding policies before formulating strategies so, again, the strategy is ineffective.
• not taking into account human behaviour, that is, the impact on the people who may be affected by the strategy, which may lead to difficulties executing the strategy.

Richard Rumelt’s book “Good strategy, bad strategy” is an old but good read and discusses in length about what is a good strategy and what is a bad one, and why template-based strategies are so bad. 

Business owners and leaders are adopting a strategy of inquiring and learning to facilitate decisions going forward.

Managing a business under the COVID 19 situation as the traditional, linear, project-like approach commerce favours cannot produce a successful outcome. Why?

1. Because there is no history or experience of this kind of situation to inform management the business how to progress the business. In other words, there is no safe ‘blueprint’ to follow for a successful outcome. Everyone is learning as the situation unfolds.

2. There are so many people involved, each experiencing different emotions that will explode if a decision is made that makes them feel more uncertain.

3. Everyone has different needs. If these needs are not addressed, riots can break out and civil unrest.

So, a different management approach is needed, one that captures, learns, and considers everyone’s emotions and needs within legislation so that outcomes are favourable (not necessarily ideal) for everyone.

The different management approach is a systemic approach, one that embraces change, uncertainty, is always acutely on the ball with the needs and emotions of their workers, customers, shareholders, legislation, technologies, and are insightful about the impact their decisions will have on all these factors.
To do this successfully organisations are continuously capturing feedback from these groups, and the wider society, and learning along the way as the situation unfolds. This collective knowledge informs the business owner/leaders what steps to take going forward. Both governments and employers provide weekly updates because they need to learn as the situation unfolds before making the next decisions going forward. 

The original question was “What are the three stages of strategic management?” but was merged and published under “How many types of strategic management are there?”  Each question has a different answer.

“What are the three stages of strategic management?”
From a technology, innovation and change management perspective, the three stages of strategic management are below in no specific order:
Stage 1: Diagnose the problem.
Stage 2: What is the guiding policy that will influence and impact any proposed solutions.
Stage 3: Coherent actions. A strategy is not a to do list, it is coherent set of precisely planned and scheduled actions for implementing and reviewing the strategy at pre-set intervals.
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“How many types of strategic management are there?”
There are too many to mention all, so here are a few examples:
Technology
Innovation
Change
Corporate
Horizontal vs vertical
International