I agree with that idea @jarvie, rent any letter anytime and anywhere without depending on another tenant who has the letter available.
Although I know it has cost you a lot of work in programming that aspect in "peakmonters", it is really successful for people like me and for thousands of Spanish speakers within the game who do not have many resources to buy cards directly in the market.
Thank you very much for the great work, I look forward to the new rental market and many successes.