A persons usefulness is a maximum of 20 years these days before they become a liability provided that all the optimum variables are achieved.
I worked this out using the following; (P) Pension, (L) Length of service, (S) Salary, (K) Knowledge, (Rr) Reputation and Relationships and (C) Company, (N) Number of people employed, (Pr) Profit.
K=Yearly evalutation result
R=Number of times involved in projects over 100K
C=Pr/N
S=C/K*R
L = (P*10)/S
Thus giving the length of service before becoming a liability from between 10 and 20 years.
Giving the whole reasoning;
Using the formulas above and the calculations below we can see that the length of service (L): 10 ≤ L ≤ 20
Pension (P): Calculated based on salary (S) and length of service (L) using the formula:
P = S * (L / 10)
Example value: If S = $50,000 and L = 15, then P = $75,000 (annual)
Based on savings for 30 years and that you'll only live 5 years after retirement.
Salary (S): Calculated based on company profit per employee (C), knowledge (K), and involvement in projects over 100K (Rr) using the formula:
S = C / (K * Rr)
Example value: If C = $1,000, K = 0.8, and Rr = 3, then S ≈ $416.67 (weekly)
Knowledge (K): Assessed through yearly evaluations or other relevant indicators. The value can range from 0 to 1, with 1 representing high knowledge.
Example value: K = 0.85
Reputation and Relationships (Rr): Qualitative assessment of an individual's reputation and relationships within the company. This value does not impact the length of service (L) directly.
Example value: Rr = 4 (10 being the best and lower numbers being how useful you are to the company)
Company Profit per Employee (C): Calculated based on the company's profit (Pr) and the number of people employed (N) using the formula:
C = Pr / N
Example value: If Pr = $2,000,000 and N = 100, then C = $20,000
What companies fail to realize however is that you can't make up for a loss of creativity.