It depends of what “optimal” means to you and your customer. For “vehicle on stop” which I setup to consider Ignition as source of “on stop” I usually set up to to report every hour which is enough and should not be an issue in regards to monthly data consumption.
Here’s how I setup the tracker to report every hour when “on stop”:
min period: 3,600 (seconds which equals 1 hour)
Min Saved Records: 1 (so it reports even if 1 I/O is registered)
send period: 3,600 seg
Vehicle moving: 0 (ignore)
min period: 3,600 seg
min distance: 0 (ignore)
min angle: 0 (ignore)
min speed delta: 0 (ignore)
min speed source: 0 (ignore)
send period: 3,600 seg
Hope this helps.