No need, really, for more than half a dozen dits. Errors can be indicated, and usually are, in a number of ways such as sending two rapid di-dits (i) or a question mark, or without any indication at all. This last is my style. I just ignore the error and continue. It may be useful to point out that there are several bug adjustments that determine the weight (length) of dits and the total number producible with each stroke of the pendulum: weight placement on the pendulum, dit contact spacing and lever travel (in the dit direction). This is for a typical straightforward design like most Vibroplexes. Some Vibroplexes have screws rather than rivets attaching the sprung part of the pendulum to the lever which allows adjustment of the functional spring force. More complex bugs like the Begali Intrepid have an adjustable attracting magnet at the weighted end of the pendulum which allows for slowing down the dit speed significantly and for lengthening the dits. Many bugs allow for a very simple adjustment to enable slower speeds. This is done by moving the weight as far along the distal end of the pendulum as possible so that the damper acts upon the body of the weight rather than on the pendulum rod or beam.