for most of the h1 interviews (it), consular look for direct client letters, recommendations etc, even the direct clint is not interested to provide such letters for short term consultants somehow people are able to manage those letter, so i still suggest you to get such letter by any means if possible. once h1 is denied its hard to re enter with tps. i had a friend with tps, he got refused with h1b n entry was denied...he was working with desi consultancy though he was not working with any direct clint that time but was employed with consultancy only ( in paper )