This is fairly easy for a blockchain analysis company to trace.
If, as you said , destination address in all transactions is the same, then the mixing via
https://exch.cx/ has no sense,you will be traced by chain-analysis agencies
Using the instant exchange may not be a perfect way to hide your privacy but if we look at the OP point of view, he is only concerned with that ordinary people can't trace him.
Other than government and the exchanges (exch.cx) themselves, other people can't trace it like you , me and other people only access to the public blockchain ? Please tell.
In this case, any Instant exchange can be suitable for him. Blockchain analysis companies won't investigate unless they are hired by someone to trace anyone and in this case, OP have no concerns about it.