Throughout my career, I have talked a lot about the principle of trust. Reading "Speed of Trust" by Stephen M.R. Covey, and "Trustology" by Richard Fagerlin has been invaluable in my education regarding trust.
My own reading, research, and informal discussions lead me to conclude that trust is the single most important element to help individuals succeed within an organization and the most important element of leadership. (Specifically, the trust an employee has in his/her direct manager; this is the key ingredient to successful, effective teams at work.)
With trust, everything is easier; without it, everything is MUCH more difficult.
I quickly learned the importance of trust (what it is, and why it is important), before training on other aspects of management and leadership.
Here's a visual representation, and my explanation of it. The horizontal (X) axis represents trust; increasing trust moves to the right on that axis. The vertical (Y) axis is what I call "chance for success"; as you move up the graph, your chance for success is higher.
Using those two axes, we can plot each of the following three categories of work...
First, Technical (blue line): actual job knowledge. Systems, technical skills, and the 'nitty gritty' of how an employee does his/her job. Sales techniques, programming languages, analytical models, systems, etc.
Starting at point "1" on the graph, you can see that if zero trust is present in the relationship of an employee and leader, there is still a high chance of success in the technical category. That chance for success increases even more as trust increases.
BUT, notice that if trust becomes negative (also called mistrust or distrust) - moving left of the vertical axis - the chance of success will decrease slightly, even in technical aspects of the job.
Second, Tactical (green line): day-to-day functions & operations of a job. Process & procedures. Informal feedback and coaching. Work tasks & schedules. Team meetings, "one on ones", etc. Approving time off and other administrative functions.
In a similar fashion, at point "2" on this graph, where trust is zero, there is still a decent chance of success in tactical matters, maybe even a 50/50 chance; but when trust is present, the chance of success increases at a quicker rate than it does in the technical category. However, if trust moves into the negative side - again, moving left of the vertical axis - chances of success for even these basic tasks decreases rapidly.
Third, Strategic (red line): things like big picture vision and purpose of the company. Supporting the company's mission. Long-term planning, and forecasting. Engagement, motivation, and career development, etc.
At point "3" labeled above, you'll see that the chance for success in strategic initiatives starts at zero. The rate of increase is the greatest yet as trust increases. BUT, if trust goes into the negative side the line continues down below the horizontal axis. It's different than just "no progress"; it can do actual damage. Damage to team productivity, culture, morale, effort, and actual results.
Think about this: would you follow a leader who you genuinely don't trust? Not only would you not follow, but you would likely participate in negative behaviors which would damage the team (rumors, speculation, undermining, gossip, etc.).
The top right corner of the graph represents the ideal state - the highest chance for success in all three categories: Technical, Tactical, and Strategic. This is the ideal state we are all striving to reach in the workplace. It is what leaders at all levels should strive for. This can only happen when trust exists at high levels.
This is why trust is the single most important ingredient for success.