Yes, each multiblock can craft one job at a time. Crafting storage just allows you to assign bigger jobs while coprocessors allow the multiblock to process multiple items simultaneously within a single job.
For example, if you want to craft sticks from wood, you craft wood into planks and planks into sticks. Without a coprocessor, the crafting CPU will craft all the wood into planks before starting to craft the planks into sticks. With a coprocessor, the crafting CPU will be able to start crafting sticks as soon as planks are available, rather than having to craft all the planks before it can start crafting sticks (as long as you have planks and sticks assigned to separate molecular assemblers, of course).
However, if you're crafting wood into planks and you want to start a new crafting job to, say, craft logic processors, you will need a second multiblock. The first multiblock will continue to craft planks while the second will handle the processors.
If you lack the resources to make several big multiblocks, a good idea is to have one big one and a few smaller ones. Use the big one for your big jobs (e.g. max tier solar panels) and the smaller ones will still allow you to craft other jobs while you wait for the big job to finish.
Another thing you can do is, in certain cases where all the resources have already been placed in the machines and the machines will auto output back into your AE system, is cancel the job. For example, if you have an automated processor setup with SFM, as soon as you send the job and all the resources are transferred to your SFM system, the processors are going to craft even if you cancel the job, so you can cancel the job in order to free up the CPU and assign another job to it.
