Tech switching is a trick that can be used to reduce the research time of a technology. It works by using the 30 days of research that can be reserved to basically skip forward up to 30 days. As it has to be frequently monitored I don’t recommend using this excessively. It can be very useful if you are trying to research something before a focus that would otherwise take longer.
In this example I will be reducing the research time of Construction I
Pick the technology you want to research faster in the first slot.
Leave the second slot to save up to 30 days.
Once 30 (or less if you want) days have been saved switch the first research to any other research.
Now choose your original research in the second slot that had been saving days.
As you can see I managed to reduce the research time by about 30 days for Construction I. Using this trick multiple times could shave off even more time for the research to finish.