Probably not “never”, but if your node is slower than 90% of the nodes receiving/sending the piece, the chances to get/send could be really low and less/not profitable for you.
For the statistics/rates, with scripts easy to run, you’ll see the rate you’ll get : Script: Calculate Success Rates for Audit, Download, Upload, Repair
So you can check your rate anytime, especially after a full month of activity (thus, the first month will be not the most representative because the new nodes need to be “vetted” by the satellittes before they get the normal traffic).
If your setting is not failing audit and uptime checking, you should be fine to run it.