Some experts charge for their time at a reduced rate (e.g. 50%) for travel, some a predetermined amount (taking the risk of delays on themselves), some only for

Some experts charge for their time at a reduced rate (e.g. 50%) for travel, some a predetermined amount (taking the risk of delays on themselves), some only for the cost of the tickets, hotels, meals, etc. There is, AFAIK and based on what I can Google, no universal answer.