Smart Checklist allows setting the template as a default for all issues per the current project as well as per issue type.
This option is available only for users with Admin permissions on the project level.
To set it up - go to the Smart Checklist menu, go to the checklist menu and click "Import from a Template".
You'll see the Templates dialog with the list of all Templates per project.
Click on template name - you'll see template details expanded.
In the "Set Default" section you'll see the list of issue types.
Click "All issue types".
Default label will appear near the template name.
Now, default templates will automatically be imported into all issues created in this Project.
Select a specific issue type you want the template to be applied to.
Now, default templates will automatically be imported into specified new issues created in this Project.