WLAN uses radio which is a broadcast medium, and so as the amount of traffic increases, so does the chance of two devices broadcasting at the same time (causing a collision). For this reason we recommend that the practical limit is closer to 20 client devices than the theoretical max. of 253 devices. Of course the actual number depends on how heavily the WLAN is used, and what level of performance you are prepared to accept.
Please note that printer ‘images’ can actually be very large, so printing a lot of documents or large documents through the WLAN can reduce the WLAN performance noticeably. Unfortunately the old typewriter style ‘text’ output and ASCII graphics just aren’t up to today’s standards.
Personally I recommend using wired ethernet connections wherever feasible, as these are both much faster and more secure. Of course it is not always convenient to run cables (such as in rented accomodation) and this is where wireless is a good fall-back.