Having a flaky working memory, as ADHD'ers do, means we NEED to do something to externalize that. This could be the much maligned advice to "write it down," but it could be visual cues in our environment, or practising memory techniques. However, you also have to be willing to forget things sometimes. If we don't purge tasks/notes from our memory systems, it's going to eventually become overwhelming. This is true whether that system is writing things down, visual cues, or "I'll remember it"