Like your social and professional network, you can only manage a certain number of truly close and valuable relationships. Of course it depends on what business you're in and therefore the size of the prize and effort that needs to go into each one.
Now let's get practical here. If you're a big multinational you probably have more clients than you can poke a stick at and you need to be ruthless in determining which client accounts you focus on. But if you're a small consulting firm or a gig economy worker then you probably need to treat every client as a key and strategic account.
The principles remains the same. Although every client account might be important, not every account is key or strategic to the degree that it demands special attention to nurture.
Working in key account management in Australia for some of the world's largest professional advisory firms like Deloitte, BDO and Mercer, I found that even the most ambitious, well-organised and well-resourced consultants struggled to manage more than a few strategic accounts at a time. These were accounts that each generated many millions of dollars of revenue, or at least a few hundred thousand, across large teams providing a variety of services to the client.
And by "at a time" I don't mean in one week, I mean over the course of years and in some cases even decades. These accounts required relationship management and team building that outlined individual team members and even the account manager.
While the consultants could service many more accounts, if stretched too thin, their ability to build those accounts into rock solid, loyal and repeat purchasing major income earners was overwise totally hit and miss.
But by focussing on just 1-3 strategic accounts they could continue to build revenue at a strong pace, usually through the introduction of new lines of business.