Look at this img:
Generally, Transmission tries to download all of items which are defined in a torrent file, concurrently. For example, if we have 10 item in a torrent file, after 1 hour, they can be in a range of 15% - 50% of progress (depending to the rate of download).
Is it possible to force Transmission to download items one by one: alphabetically or by sizes, etc. I know I can check/uncheck items manually as you see in the above image, but I'm asking for a way to do it automatically.