@jchen
I have an unlocked FPL and this is what I tested today. Note that this was just to test the features (hence may not be conclusive) as I use a different setup to handle my incoming calls.
In my online account:
-Set Rings before voicemail to 5 (max).
-Set Follow-me options to:
Status: Enable
Ring Mode: Sequential
Follow-me Mode: Call Forward when unavailable.
Follow-me number: my cellphone number
Number of rings (to try calling follow-me number): 12 (max)
Now, when my FPL number is called and is not answered, the caller will be forwarded to my cellphone. However, the first ring on my cellphone corresponds to the eighth ring from the callers side and that gives me 5 rings on my cellphone to pick up the forwarded call, assuming the caller does not hang up. Bear in mind that the reason why the default ring of 4 was established was that studies in the previous century (yes, I have lived long enough

) were conducted and about 80% of callers hang up if call is not answered between the third and the fourth call. Now in this millenium, this might have changed and Fongo needs to adapt.
Therefore, on the FPL platform, I do not see a need to increase the current 5 rings since any increase will eat up the number of rings available to the phone that is forwarded to (my cellphone in this case).
I hope that made sense. BTW, I agree to the above posts suggesting that a setting of 5 rings allows plenty of time to reach the phone, unless of course you only have one handset for every floor level that spans more than a thousand square feet.