Will sprite sequences finish playing before switching to another sequence?

I want to implement some sprite animations but before I do I want to ask how the switching between sprite animation sequences is handled… I know how to do it, but I wonder if an already started sequence is “automatically” played from start to finish before a new sequence is started, or if this timing is something I have to do by myself by looking how long a started sequence is and only start another sequence after the first is finished?

Thx for your help!

Daniela