Thank you for writing your query here.
Please note that there are thousands of sellers on Udimi and their lists vary heavily. I believe it should not take more than a couple of hours to deliver a few hundred clicks who has millions of subscribers. And there is nothing to be afraid of.
But yes, some sellers do slow runs, and some do aggressive runs. It all depends on the client's expectations. If you wish for something specific on your way, don't hesitate to discuss that with the sellers before placing the orders. The mutual conversation is always appreciated. It helps to avoid misunderstandings.