Clocks -- for playing against Yourself?

Just wondering if using a clock is a thing when learning by playing against yourself?

When first starting out, it doesn't sound like a good idea. The reason is because of cognitive load. When learning chess (or anything else) we have to remember and process a lot of new information. Because a beginner doesn't have a lot of well organised schema/patterns/knowledge to draw on, they have to process everything with the effortful, slow, conscious method of thinking (see for example the good book "Thinking, Fast and Slow"). This can overwhelm our limited capacity for holding stuff in short term (working) memory. In those early stages, anything that adds extra cognitive load, such as a timer, won't help. It will just add stress, making it harder to remember and apply the concepts we are trying to learn. 

Learning tactics is another place that I don't think a timer helps initially. To solve tactics quickly, most people rely on pattern recognition, a form of "fast" thinking that helps identify the presence of a tactic and potential solutions. Sure, the potential moves may then be checked by effortful mental calculation of moves (a form of "slow" thinking), but it was the pattern recognition that suggested the solution in the first place. To do this requires that we have learned accurate patterns in the first place. To form those patterns, I think it is better to work without a timer, taking as much time as needed to find a solution. "Don't move until you see it". Or if you must use a timer, make it a generous time, like 5 minutes for one exercise. Don't look at the solution unless you can't solve it in the full time.

Later on, a timer might help to practice time management, or to test our pattern recognition on rapid tactics exercises.

Sorry, that's very long winded, and it's just, like, my opinion.

Makes sense, and completely, as usual, overlooked before opening mouth (or putting pen to paper, or depressing the keys.)

Don't beat yourself up. It's a perfectly good question, and my answer is hardly the final word. 

That's a new and awesome idea that I have never heard of before. 

You don't need a clock to try and play fast moves when playing against yourself. If you are in a middlegame position for example, and you see a move, try playing it out. If it doesn't work out, you now know what you missed. If it does seem to work out then there's still a chance you missed something because you played so fast but if you're playing against others your level then it's not at all a dubious way of learning.

Taking time however is still the best analysis.