I have a Moto G5 with Android 7.0 and Phone 3.00.00.
It used to be the case that when I called one of my contacts, they would appear in the "Speed dial" tab of the phone app, just after my favorite contacts. For some reason, my phone app's speed dial tab doesn't show any frequent contacts any more. Only favorite contacts appear. The call history tab still shows these calls, so I am using that for now.
Do NOT ask me to look for a "Show frequently contacted" setting. I have checked both the phone app's settings and the contact app's settings and I don't see a setting for "Show frequently contacted" which seems to be a Samsung setting.