I've learned to cc direct managers on correspondence to people sluggish to respond and it usually speeds things up quite a bid.
Side tangent, what is an appropriate email response time? I've mentioned before in posts people don't read that I have almost every notification deactivated. Text messages deliver silently on my phone (just the bubble on my phone - and only if I awake it) and emails deliver silently on a monitor (just the outlook envelope on desktop) - if you need me now you need to call my cell (that buzzes my watch). Anything else, I have to intentionally seek it out.
There are days like today in which I am reachable pretty much all day - I was on my laptop from 8 am - 4 pm except when I was at the gym and I still checked my cell between sets, probably never went more than 30 mins without checking email. There are other weeks in which after my morning check-in I may not give it more than quick skims for at least a couple days. I am sure to flag emails from our team, my boss, and other leads collaborating on active projects but if you don't fit one of those criteria and you message me at the wrong time, it may be a while. Looking ahead, I see that happening if anyone reaches out too late next Wed am - good chance they won't hear back from me until midday Friday. Should I consider adjusting? I'm very pro work-life balance and speed is not a priority with my work, but am sensitive to how the lack of predictability can be perceived from another lens.
Sometimes he answers in 3 minutes, other times, 3 days.