In 0ad blacksmith for example, you need to wait until ranged damage 1 completes before you click ranged damage 2. I think it would reduce the unnecessary timing requirements if the next tech could be queued before the first has completed, so that it can automatically begin researching after the first is done. Keep in mind that this is not always the best way to get the techs since you would be paying further in advance for the same tech which makes it relatively more expensive, but the advantage