They are certainly doing that as a real profit will always work to deliver and they understands that when they show results the price will follow.
However, it's the nature of the market that people love to speculate, not only the development of the project would make the price to increase but the team should also learn to make some hype to attract investor, and they should be smart enough to do everything based on timing.

For example, this year, when altcoins is not progressive, making good announcement regarding project's development is not always attractive because investors still has the fear in putting their money and they'll rather put it in BTC when the overall altcoins market performance is poor.