I would strongly advise everyone involved in trading and extensively using USDT to read this article:
https://medium.com/@bitfinexed/the-so-called-tether-audit-that-isnt-an-audit-at-all-5a40cfcc2a75
Personally I'm don't like keeping significant amount in USDT for a long time or tokens on exchanges as a matter of fact, which of course is a problem for traders.
Stay safe!