We have 10 containers
Project A uses 3 containers and takes ~8minutes to build
7 other projects use 1 container and take about a minute to build.
When there are 3 builds for Project A, that uses up 9 containers.
If there is a Project A build scheduled next, it cannot start that as there are not enough containers.
Which leaves one container unused for 8 minutes!
Even though there is a queue of 10 builds scheduled all of which only require the 1 container.
In effect, we are paying for something we cannot use (or is this the free one lol)
If it could allow through scheduled builds that meet the free container pool, while other long running builds are active.
When a running Project A build gets close to its estimated completed time, it could resume normal queue rules.