some people use graded paper for paper negatives ( i like agfa grade 0 or 1 ) others
use multi contrast enlarging filters to adjust the contrast ..

i tend to photograph on grey days ... sometimes i flash, but not too often, i just use
older paper that may have fog otherwise, the fog cuts down on the contrast. i also
use expired / exhausted print developer ( i also use caffenol c ) which is less active
and leads to less contrast.

i've never heard of factorial development
or slmt .. i am sure that there is always more than
one way that works .

have fun !