We use ASANA task cards for Project Placeholders in our business as opposed to setting up an ASANA project for each one of our Design Projects.
Is it possible to display the parent task card that a subtask belongs to in the My Task View. On the web app it shows it but on the Ipad it only shows the name of the subtask. So if you have subtask from different project cards it is not clear what it is for. Web App is great because you can easily see which project a particular subtask relates to without needing to click into it to display further details. I like to use ASANA on the IPad so it can sit off to the side of my PC. The mobile APP (IPhone) is the same as IPad and does not show the additional info.
Would you be ok to consider create one project for each, and still keep one card for each project (you can place the project link in the card description). It would allow you to have the flexibility and confort of a project.