I know Extension is now placed under obsolete feature, but since its still not completely removed, I am using it for various purposes.
In the above regard, I would like to know whether extensions can be applied to single custom location (eg. sales-invoice-view) or everywhere only, or is there a way to apply to multiple location of my choice( sales-invoice-view, sales-invoice-form, sales-order-form etc) all at once without applying to everywhere.
The only way to do this is to copy and paste the extension and create one for each location separately.
Thanks @BawarYassin for confirming that its either single location or everywhere. Woyld have been easier if there was feature to add multiple locations like how we define gor footers & custom fields.
But since Extension are obsolete, I will work with what is currently available.