What is the recommended upgrade increments to CiviCRM 5.7 from CiviCRM 5.0?
The 5.x series has a new point release every month, with a focus on stability (generally, large new features go into extensions).

So upgrading 5.0 -> 5.7 is the equivalent of upgrading 4.7.20 -> 4.7.27, a minor upgrade and generally considered safe to do at once.