I wfh once a month and I work bloody hard on those days. Most people in my team wfh once per week and tbh I find this hard to deal with as a manager, but I inherited the situation from my predecessor and can't easily change things. As a PP has said, being away from all the distractions, last minute requests and meetings is great for the person wfh but just piles work on those who have to pick up the slack in the office and I believe that my team's productivity is far lower than it would be is people were in the same location for the majority of time. I know that's an unpopular opinion on MN though.
I do see that the majority of my team get through significant amounts of work at home but I have one person who works while looking after two children under 5 years old, which I find incomprehensible and while there is some evidence of work, I don't think she is as productive as she thinks she is. Another team member, I am almost certain spends the day watching netflix while responding to occasional emails but I have no way of proving it.
I'm happy to offer flexible working and wfh on a less regular basis. As I said, I take advtage ont his once per month and it is a godsend for getting through large nad complex amounts of work. The days around that day are always pretty hellish though, with loads of meetings squeezed into those days which, in turn, adds to the stuff with which I have to catch up on the wfh day.
I do award myself a full hour lunch break on those days. I usually eat at my desk and rarely see daylight when I am in the office so I make the most of having the opportunity on the wfh days. I live in the countryside so make sure I take a good long walk with a picnic outside if the weather is nice enough. Apart from the lack of distraction, the main advantage for me is that I avoid the 70 minute commute each way. I can close down my laptop around 5pm and immediately get on with my evening.
I will say thought that i was given a once a week wfh day in a previous job which was a much easier/boring job and I did take the piss a bit then, using the day for fun stuff but checking my phone regularly. In this job though, there is just no scope for slacking even if I wanted to.
And I have a day off today hence the ability to post here.