An essential tool? Not at all! Artists have been mastering perspective long before the Zolly App! But for the past six months, we have worked to create an app we wished for. If it seems to you like it will help, it probably will. We put a lot into making it easy to use. Regarding your question about "how to think this imagined view through manually first", it may help to review the reminders: One is that if you are having trouble, begin simply with blobs. Another is that precise positioning will be found in the three axes of a block. Soon. Another is that for most students, it requires work to conjure a new position. Take time to envision. Understanding is important, but so is the ability to "see" what isn't there — a skill worth practicing. Perhaps the most important reminder is the answer to your final question: not only are there more lessons to come about this, the whole course is about this! Drawing what you imagine... I hope this helps, Dermot; Zolly App or No Zolly App.

I've been struggling with the box of cads and some community members offered advice on how to use the blob better. You can find the thread here or maybe a bit quicker on my profile https://www.proko.com/@michael_giff/activity The long and short of it is that the blob is more used to dictate the basic perspective and not necessary used for the size (though it may help with that as well, Marshall mentions that they can be used to help with form studies and would elaborate in a later lesson) Screen grabbing and copying Marshall's example helped me a little bit as well. Hopefully someone wiser and more capable can offer you more targeted advice. Best of luck in your journey.