until your heart rate has dropped to a certain level (you'll have to use trial and error to find this level). Though your recovery times will probably increase through the session, it should ensure that the quality of your efforts remains high
You need more than one-off snapshots of your fitness levels to assess your progress properly. Races and time trials are reasonable guides to how things are developing, but they vary too much to be really useful. Races also rely on maximal effort
