I personally do not use the default RNG for large scale simulations.
There is a relevant post below,
I think the biggest issue is that it is not clear that, given the same seed, if the random numbers generated by the default RNG are repeatable. I mean, perhaps different gfortran versions and on different platform the default RNG may give different random numbers.
Also gfortran and intel fortran are likely give different random numbers using their default RNG.
So the same code will generate a little bit different results for gfortran and intel fortran.
The other thing is the period of the default RNG may not be long enough. But perhaps in many simulations this is not a problem.
If repeatable results and the length of the period of the RNG are not important to you, perhaps you could just the default RNG.