I saw many domains which are long enough in their char size. Such as these ones:
Even in mobile times, the long domains make no sense. Because most of the common sites, the traffic were gotten from the search engines.
I especially like reading these sites:
But I never tried to remember their domain names, just keep them in the browser bookmarks.
Length is not that important, but a good name makes readers have deep impression. For the domains above, I think geeksforgeeks.org is really a good domain, I can think of it easily. If this domain has become to g4g.org, even though it is short now, but I won't remember it.