Stop all actions and cast sequence when using shift modifier

Not sure what exactly to search for on the forum so I made a new topic. I’ve had macros before that seem to immediately ignore all other spells and start casting my sequence when using a modifier. I have a sequence (/castsequence [mod:shift, nochanneling, combat] Call of the Wild, Blood Fury) currently bound to shift but I feel like I need to hold shift for a long time until it casts. Any way to do what I described or speed it up? Thanks.