Two practical things so this does not become another thing you built and never evaluated.
Measure whether the email moved anyone, not whether it was opened. The number that matters is: of people who stalled at this step and received this email, how many then completed it: compared against people who stalled and received nothing. That comparison is the only thing that tells you the email earns its place, and it is easy to set up while you are building it and nearly impossible to reconstruct afterwards.
Open rates are noise now and click rates only tell you the subject line worked.
Put a stop condition on everything. If somebody completes the step, the email must not go out. This sounds obvious and it is the single most common bug in these systems, the check happens when the sequence starts rather than when the email sends, and people get told to do a thing they did yesterday. That one error does more damage to trust than the whole sequence gains.
Also worth having from day one: an obvious unsubscribe that works, and a separate stream for anything transactional so that unsubscribing from nudges does not lose somebody their password reset.
Start with one email for the biggest drop-off step. Measure it. Add a second only if the first one worked.