What would it be like if you celebrated every year, especially the first? Could you imagine waiting until five years before celebrating a marriage?
No wonder Millennials move on to better organizations quickly.
Similarly, working with clients takes constant courtship. Celebrating milestones and showing appreciation is a great way to keep the romance.
I have an excel sheet that tracks every every client by month and reminds me when milestones approach. It also reminds me how great it is to see a client work with us for months on end and how sad it is to see one go.
If you incorporate these two concepts into your organization it stands a much greater chance of excellence than many other 'important' technical tasks.