If you do say yes to everything and go over your capacity, you’ll end up slowing things down. and rushing which will impact quality. These are not good for providing a “fit for purpose” service. Furthermore, due to the nature of capacity being finite, by saying yes to something you are impliedly saying “no” to other things.
Every time you take on a piece of work, you decrease your capacity to take on other pieces of work. This might not necessarily be a conscious choice, but it’s one that you should start to think about. Saying no is not necessarily a bad thing – it means you’re focussing on what is most important for your business. It’s also a mark of professionalism and leadership to be able to have honest and forthright conversations upfront. If you do say yes to everything, you’re just delaying that tough conversation and will be breaking commitments to do so.
I think an important distinction here also comes in from the fact that not every request should be “committed” to. Some people view the fact that a request comes in means that they must make a commitment. Being able to separate the request from a commitment to get it done is a key point in kanban. Make sure the commitment point and capacities are known and a discussion is being had with the requesters as to what should be committed to. Making this process transparent goes a long way towards deeper conversations about managing the competing risks of the different requests.