I was speaking with a friend the other day about using a virtual assistant and he asked "What kinds of things do you have them do?" I started telling him about some specific-to-me tasks that I like to outsource but than mentioned that I also have them do some very basic quick tasks like google searches and phone calls. He looked at me and said, "Why don't you just do that yourself, wouldn't it be quicker and easier than typing up an email?"
The short answer is "HEEEEEEEEEEEEEEEEEEEEELLLLLLLLLLLLLL NO!!!!"
Could I call up a local store and see if they have an item in stock? Of course I could, and it would probably take about 3 minutes to do it. However, that three minutes for each task will add up and at the end of the day I might have lost an hour on tasks that "will only take a second." More importantly, a three minute task will undoubtedly break your stride in whatever you are working on, which has a multiple effect on depleting your productivity. I want you to be able to focus on only the high level tasks that can only be completed by you so taking even a minute away (which really means you have to take the time to shift gears from what you're doing, maybe look up the number for the store, call up, wait on hold while they check, then once the call is over, shift gears back in to what your were doing before). There was a great episode of The Simpsons when the Itchy and Scratchy movie was coming out. Bart was up to his usual mischief and Homer started to threaten to punish him. Bart starts saying "Ok Homer, but than you're going to have to think of a punishment, then you're going to have to make sure I do the punishment, and then...." basically over complicating the task to the point that Homer gets exhausted and gives up. All of this to say that tasks that you think will only take a minute actually do significant damage to your efficiency. So don't do it. Even something as simple as a google search can be done better by someone else if your search personalization or syntax doesn't produce the result you're looking for.
The next important point is that by writing down a task in an email, it becomes more actionable, trackable, searchable, and concise. It's a skill set that you'll use in other areas of your life and work. It's also nice that you can write an email while doing many other things. You can write emails while walking down the street, while sitting next to a sleeping partner, while eating. It's harder to use a phone in these situations.
Finally, in a world where we are going a mile a minute all day every day, sometimes the only time we can decompress is when we lay our heads down on our pillows at night. This is the perfect time to write up the 10 tasks that you want done that have been bugging you all day. This kind of brain dump at the end of the day is really good for your psyche, your mind, and believe it or not, your quality of sleep.
So stop doing these tasks and start delegating.