1) It really just depends on whether you have seen 3-4 people who enjoy writing reviews...or 400 people who are just not writers or who like to remain discreet.
2) Low volume...numbers, numbers. Well, it could be different number of visits daily, weekly, monthly or frequency of the time she is open to make appointments. I am interested to see what your perception of it is...along with other providers.
Most if not all the ladies in the life style are pushing for 4 to 5 (1hr sessions) per working day. This is specially true if they stay at better hotels and also if they are traveling. With that sort of cost, anything below 3 to 4 a day does not make any business sense.
stay away from the half an hour offering and the cheaper rates. Its just logic, someone offering 200 / half hour probably sees 8 to 10 guys. Offering 300/hr will see 3 to 4 guys per day and those at rates about 400 see less per day.
My best guestimate on your lady there with 3 to 4 per month is that she 3 per week means probably 10 to 15 guys that week if not more. Try to hit it on Monday 
Here is my opinion and perception.
It really does depend on the individual provider what the answer is, on the break point between High and Low Volume. If a lady is in charge of her own destiny (i.e. truly independent), she has control of the volume knob.
Some successful ladies will only take one appt a day and charge alot or have that one appt all day.
Some unsuccessful ladies only see one a day, cause that is all the bookings she can get. Not hating, just stating facts.
Some Ladies have a goal in mind and see a certain amount of guys a day (if their dance card is full).
The average seems to be about 3 or 4, from ladies that I have polled.
Now on the High end of the graph are popular ladies that work for agencies and are booked morning to night with 8 or more appts. That is why some really popular agency girls leave early after a few days, with a sore pussy but cash in hand.
Everything in moderation. As long as a lady provides good service, you should not be concerned about volume. Many guys like to see a visiting girl early in her schedule hoping she will provide better service the first or second day, as apposed to the last day of her schedule, when she might be burnt out (if High Volume and popular).
