If you deliver on your commitments, your stock will soar. You will gain credibility. If you are late for your deadlines, the results are also magnified. You are now undependable. Missed deadlines are always displeasing to the client.
Attorneys often commit to unrealistic deadlines.
To please the client, they promise work sooner than it is likely to be done. It's far better to be conservative and deliver the goods early, than to be aggressive and miss the deadline. If you promise the work Monday, and you have it Wednesday, the client is annoyed. If you promise it Friday, and deliver it Wednesday, the client is ecstatic. The client usually has no idea how long it will take to complete the work.