There's a fine line between persistence and simply being an annoyance, however I've seen some great examples of people balancing these properly.

Usually this comes with the ability to be very human and personal. One way I've seen this done is with old school hand written letters. On a few occasions over the past few years I've had a vendor reach out to me with a hand written letter. You just don't see them anymore, so they really stand out.

Within the context of the letter I'd consider making the ask for "feedback", not for the work itself. I would explain your situation very personally around how and why you are seeking feedback, and also make it very clear that you respect their time and understand that no answer is OK too.

There isn't a 100% solution that always works. But making it short and personal could be a nice touch.