T/TCP provides a simple mechanism that allows the number of segments involved in a data transmission to be reduced, the TAO. This test allows a client to open a connection, send data and close a connection all in the one segment. With TCP, opening a connection, transmission of data and the closing of the connection are all completely separate processes.
The highest savings result with small data transfers. This leads to the conclusion that T/TCP favours situations with small amounts of data to be transferred. HTTP, RPC's and DNS are protocols that require the exchange of small amounts of data.