As a salaried employee of a consulting firm, you are paid a salary while you are on the bench. As a contract consultant, you're usually paid an hourly rate higher than what you're paid for your salary, but you won't be paid for your working time. Sometimes, as a junior consultant, you can end up on the bench. Both in sports and in consulting, the bench is associated with a negative connotation.
You may end up on the bench for reasons beyond your control. The customer may not have signed the commitment. Or, the customer has not accepted the start date of the project. Or, in the worst case scenario, the customer canceled the project.
In particular, free time is both frustrating and annoying when you're used to the fast-paced consulting lifestyle. Most consulting companies will offer in-house training or possibly sponsor professional certifications to increase their staff and increase their billing rates. If you work at a large consulting firm, send some emails to senior managers or partners who work in a field that interests you. Once again, it's not the most glamorous job there is, but it's an important thing that makes consulting work and that could benefit you.
