While the system is convenient, it is often considered a "double-edged sword" by developers.
Everything in the Resources folder is included in your build, regardless of whether it’s actually used in a scene. resources.assets
11 Sept 2017 — So far I understand it like this: * Resources: A way of referencing assets by filename instead of GUID rerefences (the normal way) Unity Discussions Assets, Resources and AssetBundles - Unity Learn While the system is convenient, it is often
Resources vs StreamingAssets for mobile. - Unity Discussions While the system is convenient
Unity must build the entire index of this file at startup. If you have thousands of assets, this can cause significant delays (several seconds on mobile) before the game even starts.