For fuck's sake guys, workers have been wasting time since the fucken dawn of time.
Employers hire and pay their workers for a 40hr working week and they're lucky if they can get 20-30 hrs. Extended coffee, smoko, and lunch breaks, constant toilet breaks, gas bagging for hours about what they did over the weekend, continually checking their phones, playing solitaire on the computer, calling relos overseas, calling in sick, leaving early to pick the kids from school, a doctors appointment, car getting serviced, period pain, late because they missed the bus or train, compassionate leave for the family cat that died on the weekend, working-bludging from home etc the list of excuses and reasons is as long as a fucken roll of toilet paper.
So as an employer, it should come of no surprise when a WL wastes your time?
If you pay for 30mins and only get 15mins of productivity then fuck yeah! fire her ass and find another worker. If you pay for 30mins and get 25mins then yeah, that's fucken industrial relations in a nut shell.