Does anyone know how the league (and cup) fixtures are drawn up?

Is it really random?

This season, when I look at my league fixture list:
first-leg fixtures = 6 away matches (all except the first one) and the second-leg fixtures mean 7 home matches in a row.
Is this just chance? Or is it a game setting?
See my schedule for upcoming return fixtures.

Unfortunately, it happens all the time...