The end of expansion Trials (Singularity Reactor, Royal Menagerie, Dying Grasp and Final Day) could most definitely use a proper ilvl limit.

For Alliance Raids, I think the best option would be tying mechanics more to Boss Health rather than time. Like the ARR Alliance Raids for the some part will start doing their main mechanics when they hit a certain health % rather than waiting a minute or two.

Though this could cause some problems with some bosses, like Scylla in Syrcus Tower needing all the towers to be hit with enough lighting balls before her add phase that hasn't been seen in almost a decade.