I've found that emails that I write with a written suspense on them aren't answered any sooner than ones without a written suspense. Over time, I've tried to figure out how long to wait between successive follow up emails.
-If it is something critical, I may email again the same day or call.
-If it is pressing but not critical, I usually email again within 2-3 business days.
-If is is something I'd like to resolve in the near future, I may wait 1-2 weeks.
I realized everyone is different, and that contacting someone about and issue too often may lead to them treating your emails as less important. Alternative, contacting someone too infrequently can lead them to forget about the issue and not get back to you.
What is a reasonable, professional, and efficient way to time follow-up emails?