Please be careful when designing your lights
There has been a growing "designer" trend to assemble split socket adapters in odd configurations such as the one photographed here. The technique is fine, if you know what you're doing or the people you sell the light to know what to watch out for, for the life of the fixture.
Most people are unaware that standard junction boxes should really not receive any more than 600 watts through them. But as you can see in this 20 socket fixture, that can be exceeded rather quickly.
If those bulbs are only 25 watts, that's okay. That's 500 watts. But if those are 40 watts. let's say, that's 800 watts, and if they are 60 watt bulbs, well, that's exactly double what it should be at 1,200 watts.
When you buy a commercially made light, makers try and dummy-proof the fixtures so that this error could never occur, using less sockets than could ever exceed the maximum even with 100 watt bulbs, and putting hard to miss recommended wattage stickers on the sockets themselves. But when folks build them on their own, they are usually not aware of the hazards.