No, you got the right of it Babel.
The sanctum helps make declarations. The better your sanctum, the easier it is to make varying declarations.
For example, if you want to make a ritual research based declaration from Lore (to "double dip" from Lore for complexity) you must have an Arcane Sanctum of value equal to or greater than the difficulty for the declaration. So if you have a Great sanctum and it is a Good difficulty, you can roll your Lore (which may be Superb) to try for the declaration.
Specific passage:
As described in Scholarship (see page 142), the quality of a workplace determines the highest possible difficulty of a “question” or project that you can pursue there.
In this case the "question" is your declaration.
You can assume to have a workspace equal to Resources - 2. So perhaps a Thaumaturgist (in Submerged) would benefit from having a Superb Resources in order to have a "free" Good quality Arcane Library and a "free" Good quality Arcane Sanctum (two declarations where you roll Lore). Even if it meant lowering Lore by 1 (at submerged you can have 2 superb, 2 great, and 2 good skills, so you could go Superb Lore, Resources; Great Conviction, Discipline).
A straight up Resources declaration could be purchasing some component. You could also use Contacts to take that component and have it blessed or imbued by "this guy you know."