IMHO (having managed small teams) a manager of technical team members needs to be able to accurately estimate how long something will take and the variance on that estimate. This is a core part of the manager's job. If a manager isn't technical enough to know how to do the tasks themselves if they had to, that manager should not have a job IMHO. This is part of what sets engineer-led companies like SpaceX apart from their "dinosaur" competitors and why SpaceX seems to be 10x better in output.