Limit switches keep activating

[JAZZCNC]

This will almost certainly be a noise issue not a faulty switch.!
Even the cheapest nasty switches can work ok and not trip, they just aren't very accurate. Also because there cheap and your only running 5V thru the switch's then this low voltage can cause the contacts of the switch to fuzz or burn thru them bouncing when machines working. After awhile this translates or worsens into a false trip. Setting the De-bounce helps handle this false signal.

If using Mach3 then try this first has a temp fix. In general Config in top right hand corner set the debounce interval. If at zero or very low number set higher IE: 1000. It's not unusual to have it set to several 1000's if needed has 1 unit = 40 microseconds.

Next check to see if any mains power cables run directly along side any input cables. If so then separate.

One of the reasons this happens is because the limits switchs don't get much use so it's a good idea to flick the swithcs every so often to give the a blast of current and clean the contacts. Putting some small capacitors across the switch's can also help avoid this if it continues. Thou I think you'll find de-bounce works.