Does it assume that sketches are OK and start calculation with bodies?
Or does it poke inside sketches, and if so, what does it do with Blocks?
You're question is a little vague.
Features in a part are evaluated in the order that they're created, regaurdless of whether they're sketches, reference geometry or model features. The solving process happens when when the user prompts the model to rebuild, when the file is saved or when a part is opened in a resolved state.
Blocks are update across when you finish editing them
Sketch relations are solved simulteneously in real time whenever the sketch is modified.
Assembly mates are solved simulteneously as components are mated or moved
Assembly features are solved after the assembly mates and in the sequence that they appear in the assembly tree.
Appearances are solved each time at feature is added to the tree
Decals update when the component with the decal is loaded into memory for the first time or when the path to the decal changes or other settings are edited in the decal property manager. Changes to a decal in one configuration (including deletion) do not affect the decals in other configurations.
The stoplight rebuilds changes only from the last rebuild. A control-Q rebuild will process the entire model from the top of the tree. Get in the habit of using Crtl-Q often.
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