Single frame distributed is only good if you have multiple machines and you want 1 frame faster, which is usually high res - 4,6-12 K. This introduces a lot of lag into your render. The packages must travel through network to the master computer instead of dumping them into ram directly, the master must tell the slaves what to render etc...
So Single frame DBR is the way to go for high res frames.. but in terms of efficiency, 1 node is better always.
Feel free to try out our renderfarm as well, you get a free trial, maybe it's something that you will find useful in the future.
Can check it out on my signature link.
Good luck with your projects!