IMHO knowing when to accept defeat in a professional setting is one of the most important skills a generalist can learn. As with everything in tech the answer is "it depends" :)

When possible I'll ask to be either continue to be involved or kept in the loop until a solution is found.

By reaching these boundaries at work it provides me avenues of exploration in personal time to understand where my knowledge gaps are - and quite often find new interesting subjects along the journey.