How fast you progress to in any particular training session will be based on the goals of the session and what your body & mind have available to deliver on that day. I like to give my clients workouts that are what I call "progression on feel". This allows them to listen to their body and progress to their limits for the day or if the body is a bit off, then just progress to what is available. I believe this helps keep injury potential down and continues to teach the athlete to listen to the signals their body is sending so they can keep training or recovering if that is the case.
Progression workouts are really quite simple, you start off at a pace you can handle and increase your intensity as the workout progresses. They are great for teaching athletes how to pace themselves at the beginning of a training session, so they will have enough energy to finish the session as fast or faster than they started. It is much better to be dictate the pace you are going to move at rather than have the pace dictated to you because you went out too fast.
For those that train with power or heart rate, you can easily measure whether or not the intensity is increasing. While going on feel is great, the numbers don't lie and a good tool to use to compliment your training. Over time your feel will get better as your ability to gauge your perceived effort improves. This is important because you do not want to be a slave to the numbers and what happens on race day if technology fails you? You should have a very good idea what a particular effort feels like, and how long you can sustain it.
Remember that consistency in training is one of the keys to improvement. This coupled with a balance of stress plus recovery will enable an athlete to progress their training throughout the year. So try implementing a few "progression on feel" workouts during the coming weeks to help maximize the training that you do.
Train Smart... Race Fast!