That helps . . . It sounds like you are probably shooting .25 caliber at pretty high power, so you will be using a lot of air. Not as much as big bores, but still using a pretty good amount per shot.
I'll provide a bit of an explanation to help you understand it better. When thinking through "air" for shooting purposes, we have to consider both the volume of the tank, and the pressure of the air. To best do this, I like to use a unit of simplified unit of shooting air that is best called the "bar-cc" of air. This is simply the cc's of air we have multiplied by the pressure in bar. The big tanks are pretty much all 9L of volume (regardless of the stated "cubic feet" of air - that is a whole separate post, but the sticky one on tank volume addresses it), and a full fill is 310 bar (4500 psi). So a full 9L tank holds 2,790,000 bar-cc air - 9,000,cc at 310 bar. It sounds like a lot, but you will be using a lot, and we don't get to use all of it . . . we do not use the air below the bottom of our fill point. If the gun is refilled at 2500 psi (~170 bar), then we can't use the 1,530,000 bar cc below that point - leaving us with just 1,260,000 bar-cc of usable air in the tank.
Then we have to look at the power and efficiency levels of or guns. Most US airgunners people talk about efficiency of airguns in the units of FPE / CI, but that unit does not work well with bar-cc units of air - fortunately they are easily converted (1 FPE / CI - 16.38 bar-cc / FPE). Most long barreled high power guns will run around 1.1 FPE / CI, or about 18 barr-cc / FPE, although there is a lot of variability in efficiency in guns. Since it sounds like you will be shooting at around 60 FPE or so, you will be using upwards of 1,100 bar-cc or air per shot.
Put that together, and a 9L tank that is used to refill the gun above will get about 1,150 shots out of a full fill - almost certainly less if not shooting tethered, as there are losses every time we vent the line to disconnect the tank. So unless you are willing to stop shooting while the compressor refills your tank, you will need multiple tanks. The number of tanks depends on whether you are able to refill through the day, and if you are comfortable continuing to shoot while the compressor fills another tank. You didn't say what compressor you have, but at $4500 it is probably up to the task either way. Consider the refill time into your decision, whatever that may be.
You can get 12L tanks that will give you more shots per tank, but they are proportionally more expensive and still won't get you through a day. Personally, I'd prefer to have more lighter cheaper 9L tanks than maybe one fewer 12L tank and pocket the savings.
In the end, you are going to have to think through what you want to do, but this should help you do that . . .