Robert,
Think of the variable cycle job as a stopping point in the history database.
It sounds like you are using variable cycle along with Cycle Accumulation. So in this instance, I'll assume Monthly Job has a history item looking at a Daily Job. This history item has the Monthly Job set up as its variable cycle job with a -001 relative cycle and uses cycle accumulation to accumulate any history items through -30.
Let's say you ran things in this order:
Daily Job - 20190529
Daily Job - 20190530
Monthly Job - 20190531
Daily Job - 20190601
Daily Job - 20190602
Daily Job - 20190603
Monthly Job 20190630
When the June 30 Monthly Job runs, it will accumulate Daily jobs up until it hits it's stopping point of Monthly Job -001...which in this case would be the 20190531 job. You don't have to worry about any histories prior to 20190531 being added because your variable cycle job is serving as the stopping point. Remember that variable cycle and most recent cycle indicators go hand in hand so just make sure you test all scenarios.
Hope I didn't confuse things more.
Good luck!