The reliable default: mid-morning, midweek
If you have to pick a slot blind, Tuesday to Thursday between roughly 10am and 11am local time is the safest bet. People have cleared their inbox but not yet hit the afternoon slump; Monday is for catching up and Friday attention is already drifting toward the weekend. It is a default, not a law, but it fails less often than any other blind guess.
Match the meeting type to the energy
Deep, decision-heavy conversations belong in the morning when attention is freshest. Status updates, informal catch-ups and low-stakes calls survive the afternoon fine. Scheduling a hard strategic conversation at 4pm is fighting the clock — move it earlier and it will go better for reasons that have nothing to do with the agenda.
Protect the maker's calendar
For anyone doing focused work, a meeting dropped into the middle of the morning does not cost one hour — it costs the two hours of flow on either side of it. Cluster meetings at the edges of the day or on set days, and leave protected blocks intact. A booking page with limited windows does this automatically: you decide when you are bookable, and the calendar enforces it.
Time zones change everything
The moment attendees span time zones, "the best time" becomes "the least-bad overlap." A 10am slot for you might be 10pm for them. Always show times in the other person's zone, confirm the zone in writing, and when the gap is wide, rotate who takes the inconvenient hour rather than always making the same side stay up late. A good booking page does the conversion for you so nobody does timezone math in their head and gets it wrong.
Let the other person choose
The single most reliable way to find a good time is to stop guessing and show real availability. When someone picks from your open slots in their own timezone, you skip the back-and-forth entirely and they self-select a time that actually works for them — which is, by definition, the best time.