I prefer 1:1 when there is something relevant to discuss (merit increases, onboarding, significant problems). Personally I believe this is the best way the manager/employee relationship should function. Email and daily interaction should be more than enough to maintain communication on projects, work, etc. The clear sign of a good manager is the less 1:1's the better. That means the manager is respected enough by his subordinates to know what is going on with his team and the team can collaborate enough to solve problems without constant involvement from the manager.

When a manager has weekly 1:1 meetings, time to find a new job...and fast. That is a major red flag if the manager unable to keep track of the team OR upper management is getting ready for layoffs.

In fact, when go through the interview process once question I ask is are their views on 1:1 meeting, how often are they, are they mandated by upper management or just the manager's preference.