This year we have 6 limit switches on our robot and we may add a 7th (this is mostly limits for the maximum positions of our tube manipulators). This seems to me to be a large amount. How many does your team use?
Besides being a lot to wire up and keep track of, the limit switches are more-or-less flimsy and do break or stick occasionally. Our mechanical group lead has strongly requested us programmers to make an override operation to the limits in case on breaks mid-match and we can't operate the robot correctly. They are also hard to mount, but they are easy to buy and flexible to use. They offer clear, definite feedback to the position of a mechanism, which can't always be achieved with potentiometers or encoders (wandering, needing to be reset, coded differently, other complications and complexities).
This was especially realized by our team (especially programming!!) after using an encoder last year for determining the position of our kicker. Our kicker had quite a loose chain, which would kick itself more and more loose, making our encoder inaccurate. We updated the max and min encoder constants countless times and the robot often froze in autonomous as the kicker reached its physical stopping limit, but the programming thought it still needed to swing farther. The electrical and mechanical groups never put any limit switches on, despite my insistence. So this year, we have 6 of them!
What do you think?
The most important deisgn criteria is always performance in any of the parts / systems we design. But we do try to abide by the saying -- if it doesn't look good (right), it probably isn't good (right). - Adam Freeman [more] 
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