Unlike the practices followed in government and quasi-government establishments, where there is a concept of an (automatic) annual increment system generally followed, the private and unorganized sectors differ. In government and quasi-government sectors, an employee is appointed to a post carrying a specific time-scale basic pay, which is well indicated along with other allowances. Except in rare cases where an employee's performance is found to be dismal, attendance issues arise, misconduct occurs, or disciplinary proceedings are underway, an annual increment of pre-fixed sums (usually from the date and month of joining) is typically authorized. An average or below-par performer could receive an increment.
On the other hand, it's not the same in the private and unorganized sectors, where well-established firms do not authorize automatic periodical increments to employees; it must be earned. Many follow their own 'performance appraisal'-based increment authorization systems. The periodicity and quantum vary among different firms. In this case, there is often a comparative study of peers across sectors.
At the same time, it's incorrect to conclude that the quantum of increment diminishes as employees rise in the hierarchy. While there may be some instances of a slowdown, it cannot be a general rule. In an era of CTC and the fact that employers nowadays offer 'stock options' to middle and upper-level cadres, it's only a myth to say that it slows down. These cadres are provided with various other forms of incentives too, which cannot be missed.