Best I can tell not really it more linked to RPM as the main ingredient followed buy other issues of HP , tuning ,cost ,cooling are all factors but for most modelers it is RPM , tuning and HP as the main issues

Nitromethane is a chemical liquid which has a small part carbon type molecule (carbon hydrogen mix or carbohydrate) to burn and nearly 50% part of the molecule is oxygen, which is used to burn the carbon molecules and the rest of the molecule is Nitrogen which heats up and gives more compression
The atmosphere must still supply some extra small amount of oxygen to get a complete clean burn but Nitromethane is capable in certain situations to burn although less efficiently without outside oxygen from the atmosphere or elsewhere
There are other ways to achieve similar results
One method is if the engine was put in a static base where weight of steel containers holding liquid air components are not an issue and the nitromethane could be replaced with LOX (liquid Oxygen) and NOX (liquid Nitrogen) and this would achieve the same purpose to supply extra air components into the engine than what the engine can bring in itself with carburetter or similar aspiration methods .

Using only bottled gases and hydro carbon fuels like Methanol Gasoline Ethanol,natural gas etc it would be possible to get fuel to burn without a carburetor or air from atmosphere but it's weight is too much for modelers
However tuning would be super easy and engines would rarely quit or flame out


Another method is similar to above in using nitroes oxide gas but again weight of bottle to store nitoeos oxide is usually too heavy for modelers

Mechanical methods for larger engines can achieve similar results with turbos or blowers(superchargers) which would force more air into the engine
However complexity and weight make this more likely in engines of 1000cc and above

Methanol the main ingredient modelers fuel has a molecule which is roughly 50% carbon type (carbohydrate)and 50% oxygen and can easily do the exact same job of suppling more horse power from burning more fuel as Nitromethane and at a far cheaper job with simply increasing the compression ratio of the engine
However this often makes the motor more difficult and sensitive to tune .

Also most modelers engines for the USA market often are relatively low compression ratio for medium to high nitro use
In order to increase the compression ratio it would require a machine shop to bring the typical compression ratio ~9.5 : 1 up to more powerful ~13 : 1

Motors made for European market can often be made with higher compression as the majority use low or no nitro due to excessive higher costs of nitro in Europe
Often four times more costly than USA

The addition of lots more nitromethane means the more mechanically challenged type person you are the easier and more wide band will be the tuning of the glow engine
This is because the engine would getting its oxygen from a fixed source the fuel itself at a steady rate rather than from the air which can change hourly in temperature and humidity and require constant tuning changes

Also using higher nitro will gain some extra power as a side benefit and importantly it will be more the power will tend not to be so peaky like zero nitro fuels and a noticeable gain in low end torque at the lower RPM such as is needed in 3d work

The higher the RPM is made to go the more the engine will find extracting oxygen from the atmosphere more difficult .
Then the inclusion of high nitromethane rates there will have more benefits to ease of tuning and the RPM will be increased in a feedback loop

As often the smaller motors will turn at higher RPM it would be easier to tune the engines with the Higher RPM with more Nitromethane in the fuel

So a OS90 VR DF 15cc engine (large motor )doing 24,000 rpm will often use 30% nitro and a more sedate OS40LA coul