zback as an EC, I did a lot of T&M for a few good clients. Office/billing time was not chargable directly, but layout, drawings, etc., was billable. Both the clients and I liked the fact that T&M eliminated the estimate/proposal & acceptance paperwork, and provided prompt service.
Material pickup was billable, rate was dependent on helper or mechanic/j-man making the trip. Most materials were delivered to the jobsite by supply houses, sometimes daily.