How much they are around matters much less than whether or not they have set a clear strategy for the company, whether their direct reports have the autonomy and ability to execute on their pieces of the strategy, whether they have built and maintain a culture that keeps the organization productive, and if they are available to their direct reports when needed.

If all those things are true, then they can be in the office as much or little as they want. If one or more of those are missing, then the CEO has work to do.