When to use additional instances in Compressor

One should think by increasing number of instances (I have the option to select 2) should speed up the compression process. Larry Jordan said in an article that when compressing Pro Res, multiple should should be turned off. So when to use it ? Is there somone who could clarify this for me ?

I leave it on, but set it according to the user manual. I get really good performance. Rarely am I encoding ProRes files with Compressor, but when I do I leave it on and still have good encoding speeds.
help.apple.com/compressor/mac/4.3/#/cpsrd42eb6d3

Pay attention to the Note at the bottom of the page.

Í encode Pro Res all the time, but I can hardly see no speed gain on or off. Thank you for reply.

Yep, Apple's apps are geared to work with ProRes as fast as that's going to get. I've not noticed leaving it on slowing anything down. Just if a codec won't use that feature (must be a codec that can segment during transcoding), that function simply doesn't get used.

I encodee Pro Res tóo H264, so that combo maíy not taka advantage of instances.

That's going to take advantage of the H.264 hardware encoder built into your i7 or i5 processor.

FCPX.guru wrote: That's going to take advantage of the H.264 hardware encoder built into your i7 or i5 processor.

Í dó not undestand what i7 or i5 is, but I have Mac Pro 2013 quad, and I can not see any performance gain when turned on.