Other shows are filming with the actors not being six feet apart. I assume with rigorous testing.
I've been on a film set in July, the only differences from usual were that we all had to be tested (I got tested on a Friday, the shooting was on Wednesday, got my results on location but had been told that I would have been warned on Monday had I been positive) and everybody was required to wear masks while indoors at all times unless you were actively working (either in a scene, or you were part of the crew and doing something…To summarise, you had to wear a mask while waiting, basically).
The scene was set in a huge ballroom with a lot of ventilation, but I don't think this was strictly because of the Covid-19 issue, probably just a lucky coincidence.
This was one of the firsts productions to resume in Italy after the lockdown, the security personnel were very strict on masks in the beginning, starting with a recap of the Covid-19 safety precautions first thing in the morning, but I noticed things were way more relaxed after several hours.
I'll be on set again in a week or so, it will be interesting to see how things have changed in the past couple of months.
Please note that this experience concerns a single production in Italy, other productions may do things differently, especially in other states.