Multi-Threaded Jobs

I have a couple of tasks that have the need to process continually thousands of items, typically using multiple threads.
Currently, without hangfire, we have a hourly cront task that spawns a request that fetches a x amount of items and spawn y amount of thread to process them. Before another request comes in, the threads are stopped so a new set of tasks will spawn next time.

With hangfire what is the best approach for this, assuming that I need multiple simpler recurring jobs, and a few of this processing jobs.
Should I keep the same approach, to have a hourly jobs using the same strategy, or should the hourly job just en-queue tasks per each item?

Is there any issue to use Task.Run or other Threads inside the jobs on hangfire?