Conversational Standard Volume vs. Low Volume?

When going through the TCR Registration process and creating a campaign, there is an option for Conversational Standard Volume vs. Low Volume. I am a bit confused. We will only use text messages for communication with customers regarding scheduling quotes and jobs. Normal, casual conversation. No "marketing campaigns." We will likely be sending less than 15,000 messages per month, but I feel like when we are having a normal conversation with a customer, we may send more than 6 messages per minute during a conversation? Curious on if I should choose the Low Volume option and just deal with the 6 message limit per minute, or if I need to get the Standard Volume option. Any guidance will be appreciated, thanks!