There are some inherent problems in the peanut butter approach if you apply the same tactics to all parts of a business. The company that simply reduces 10% of its workforce without considering that certain departments may need more workers because of greater productivity generally makes a mistake.
Another way that the peanut butter approach is mentioned in business is when companies give raises. Instead of determining raises on a merit-based system, some companies give the same raise percentage to all employees. This can have unfortunate consequences because it rewards employees that may not merit raises and at the same time may not encourage employees, who have worked very hard, to stay with a company.
It frequently is used by managers who cannot make decisions so they equally mete out criticism, punishment and/or praise to all whether it is merited or not. It is often a sign of weakness in a manager.