[Freeswitch-users] Common/Reasonable Assumption on DID/Channel over-subscription

Hello All, just throwing this out there. What are people generally using these days when designing their services, esp. those that require a user to call a DID to access their system, similar to calling card services. There was a time when this used to be 50 to 1 for DIDs, and about 10 to 1 for number of channels bought in SMB with IP-PBX. I believe this would have changed today and assuming a service is pretty popular, the ALOCs are longer due to cheaper rates and convenience of calling. Does anyone have any real world numbers they can share? Is 10 to 1 a good ratio to ensure a user practically never gets a "circuits are busy"? Thanks in advance