At a firm I worked at in LA, summer hours were from Memorial Day to Labor day and it meant we were free to leave at 1 pm on Friday.  One of my co-workers worked for Wilson Associates in NYC (solely an interior design firm) and she said they had the same summer hours there.  I hear it's quite common in LA and NYC, being from the Midwest it was a new concept to me.

Where I worked it meant, I think, either half day Friday in the summer or a few extra hours each day and Friday off. Then the boss decided to make the arrangement permanent! I think it was my lazy European ways acting as an inspiration.

It makes a lot of sense since I like to put in more hours earlier in the week and reduce demand as the week goes on anyways so we have adopted this schedule too. Fridays become a work day if needed to, but usually not!

9 hour work days/every other Friday off.

For those of us on salary, we rarely, if ever, take the Friday off. Work doesn't stop just because we work an extra hour on most days. It also is a little awkward from a client perspective. They still need to be in touch on those Fridays. Also feels strange walking clients through an empty office on a work day. Makes the office seem a bit lazy. Not really a fan of "summer hours" personally.

we do 9 hour work days Mon-Thurs then 8-noon on Fridays until Labor Day

It's kind of nice, but i kind of have a feeling production overall takes a decent dip during summer hours

Probably not enough to make a significant difference compared to how its a nice benefit to offer

For those with a family, being able to have that extra time during the summer is really nice