There is no specific rule on a lifespan of a wrist strap. Any company policies should be followed on replacements but a good general rule of thumb is to look at the overall use, possible wear and cleanliness of your individual wrist strap.
Often companies determine a guideline on replacing them annually, semi-annually or quarterly.
This small change can often feel good for those that use a wrist strap daily and especially those who share a wrist strap at a common workbench or workstation.
It can be a small investment in employee satisfaction to have an upgrade to the tools and equipment on a regular basis. Replacing a wrist strap can be a small but strong signal from management that the company cares about proper ESD procedures.
