I already suggested something like this:
But it doesn't have to be that way, it is just a suggestion. My point is that we have to define output and frame range much earlier in the workflow, and that will allow to run multiple render target jobs at once.
In production (and believe me, I'm 10+ years in it), current system is not flexible at all. It has to be!!! Flexibility is the most important parameter, so ability to define multiple parameters at once is big advantage too. Standalone is nodal and what is the point not to use that advantage?
When doing this render job system, you have to think that way.
What is important:
1. Flexibility
2. Simplicity
3. Overrides.
And common workflow goes this order:
1. Define render parameters/settings for each render target
2. Define frame ranges
3. Define output paths
4. Define file types
5. Hit render
First 3 stages are unique parameters for each render target/pass/layer call it as you want. When you define unique parameters, then we connect further to the render job where parameters are common for all render jobs. And that means file types, skipping rendered, compression, overall frame range override... etc. It is not acceptable to choose if render is tonemapped or not at this stage. Render job has to respect "Camera Imager" decisions. What if I want one render target to be tonemapped and other not? So, render job parameters have to be common for all render targets, it has to be simple, it has to have checkboxes to select render targets that will be rendered, and one big "RENDER ALL/SELECTED" button. Hit it and go to pub.
Maybe, I missed something, but I believe that something similar to this kind of workflow will make life easier to all.
I'll use this discussion just emphasize some bad things related to overrides/render layers/mattes... Current render layer system is kind of ok, but why there is no option to group objects and define object layer parameters? So, what will be good? It will be good to be able to group objects in the partition and to override common parameters for that group at once with Object Layer node. Also ability to override all the materials in the group/partition with single material.
That gives flexibility. When Object Layer/material node is connected to the Group/partition you override parameters of the objects in the group, when there is no ObjLayer/material connected, group respects unique materials/objLayer settings of the objects in group as defined.
Also, matting system like CRYPTOMATTE or similar is very, very, very desirable.