It is generally possible to create and upload as many List and Task Templates as you require since many organizations use task templates to map to different products or services sold, as well as their different Board Types. In most cases. List Templates are used to map to the Board Types that require a different set of Lists and behaviors, so will only require enough List templates to map to existing Board Types.
There is a limit to how many templates are displayed when choosing to import a task template manually, which is 500 records. In the Taskfeed Templates list view, up to 100 records will be displayed per view. We recommend switching the list view from "Recently Viewed" to "All Task Templates", "All List Templates" or a custom view to limit your results.
If you have multiple templates uploaded, we recommend creating a Custom List View in Taskfeed Templates to display only those templates that are currently "Inactive". This will show you what's not being used and can perhaps be deleted or modified since these records do count towards your Salesforce data storage limits. Here's how you can do this in Lightning:
From the Taskfeed Templates tab, go to List View Controls and click New.
Follow steps 1 through 6 of Create a List View in Lightning Experience.
Then for step 7, create a Filter with these values: select "Active", "equals", "false". Click Save.
Under List View Controls again, click "Select fields to display" and choose those fields that are relevant to this view, such as Template Format, Board Type, Last Modified By etc.
If you're working from Classic, this article shows how to create the list view in Classic and the filters and fields to display are the same as above.See also: Salesforce Files and Salesforce CRM Limits.