If the bracelet is too tight, it will place unecessary stress on the bracelet. This is especially true when the bracelet has a toggle clasp, and the wearer has to try to pull the bar end through the round part of the clasp.
The proper way to find the correct bracelet size is to measure the wrist and add 1 1/2 inches. If using large beads (10mm or greater) you may need to add length to accommodate the large bead diameter.