No. If you are admitted into the U.S., you will be given an I-94 (small white card) which is a record of arrival/departure. On the I-94, the INS will mark your date of admission and your maximum period of stay in the U.S. Ordinarily, the initial period of stay will be no longer than 6 months, although you may be able to obtain an extension up to a maximum physical time of 1 year. After being present in the U.S. for 1 full year, you must either leave the U.S. or change to some other visa category.
Even though the B-1 or B-2 visa is valid for 5 years, you may not be admitted if the INS believes that you are using the B-1/2 visa to actually live in the U.S. For example, if you stay the maximum period allowed (say 6 months or 1 year) and then go abroad for 1-2 weeks and seek to return to the U.S., the INS may deny you readmission.