“When planning for a year, plant corn. When planning for a decade, plant trees. When planning for life, train and educate people.” - Chinese Proverb
Early in my career, I supported the technology for sales teams and marketing departments.
In one company, the turnover rate for one of the sales team roles was very high. I watched 12 salespeople cycle through the role. Finally, a new sales person came onboard who sold more in one month than everyone else combined.
The management became more enthusiastic and chose to add a second sales person hoping to double sales... but the plan failed. The second salesperson provided less than 10% more sales per year compared to the top salesperson.
This introduces us to the problem of how to calculate sales capacity.