For systems that access global properties like unit colour and time of day, a separate system should be used to manage concurrent access.
For example, lets say a hero has 3 abilities.
Ability 1 locally changes the colour of the caster to green and the target to red for the caster owner for 10 seconds.
Ability 2 globally changes the colour of all targets to yellow for 7 seconds.
Ability 3 gradually changes the colour of the target from blue to yellow over 3 seconds.
If all 3 abilities were cast at the same time on a single target, what colour should he be for what player at any given time? This is why a separate system is needed to manage this property, as otherwise you could get any number of strange bugs occurring including loss of colour when inappropriate or low priority abilities overwriting higher priority abilities with their colours.
Time of day is even worse as that can directly impact game mechanics such as life regeneration, mana regeneration and even the usability of some abilities.
If a hero casts an ability that changes the time of day to night for 30 seconds at the same time another hero casts an ability that changes the time of day to day for 30 seconds, what should the time of day be? For balance you might want both abilities to cancel each other out where their durations overlap and restore time to normal.