You should edit the topic if you want a new feature to label it such.
As the other poster pointed out... You have the option of Tixati managing the queue (in the background)...
As long as the transfer is not STOPPED it is being managed and looked at in the background.
You have two main sets of option (auto manage queue) which has ACTIVE and QUEUED as a possible status for both downloading and seeding, and
(recycle slots in queue) this option is useful when you only have a set number of transfers and you want to utilize all your slots notwithstanding your set "X" slots download "Y" slots seeding... This is usually turned off when people want to keep minimum X downloading and Y seeding.
N.B. If these are both DISabled you are in full control of the transfers, perhaps that's what your current settings are?
If you read the https://support.tixati.com/
you will see that the queue management does all but TTL for your requested change. There are permanent slots, used slots, and temporary slots (as other poster pointed out to be used when your bandwidth isn't being fully utilized).