A sequence is not five emails saying the same thing. Each step has a role: the first email makes the case, the LinkedIn visit and connection put a face on it, the follow-up adds a new angle, the call catches whoever reads but does not write, the breakup closes the loop.
Data from hundreds of thousands of lemlist campaigns says the same thing every year: adding a second channel lifts reply rate more than any copy change, and the fourth to sixth touch produce a large share of the replies.