The post describes different configuration options of SXA Asset Optimizer and their influence on each other.

Asset Optimizer configuration

Each row represents example configuration set and the end result. Some options have priority over the other.

Asset - contains cases that I wanted to highlight.
Global - global settings set on /sitecore/system/Settings/Foundation/Experience Accelerator/Theming/Optimiser/Styles or /sitecore/system/Settings/Foundation/Experience Accelerator/Theming/Optimiser/Scripts
- available options: Concatenate, Concatenate And Minify, Disabled
Site - site specific settings set on Page Designs item, field Styles/Scripts optimizing enabled (section: Assets Optimization)
- available options: Default, No, Yes
Theme - theme specific settings set on a theme item, field Mode (section: Theme)
- available options: On, Off, Inherit from System, Inherit from Site
Result - outcome of configuration set. YES indicates assets will be processed.

Asset	Global	Site	Theme	Result
Site - explicitly disabled
script/style	`[ANY]`	No	Inherit from site	NO
Site - explicitly enabled
script/style	`[ANY]`	Yes	Inherit from site	YES
Site - use default settings (global)
script/style	Concatenate And Minify	Default	Inherit from site	YES
script/style	Disabled	Default	Inherit from site	NO
Theme - respects only global
script/style	Disabled	Default	Inherit from system	NO
script/style	Concatenate And Minify	Default	Inherit from system	YES
Theme - explicitly disabled
script/style	`[ANY]`	Default	Off	NO
Theme - explicitly enabled
script/style	`[ANY]`	Default	On	YES

Summary

Hopefully this table made it easier to understand how to configure Asset Optimizer. If you have any questions, just ask.