I just got done reading an article in August's copy of Bicycling magazine. The article supports my previous blog (Half Time Break) regarding the importance of taking a recovery week mid-season. Jason Tullous, Carmichael Training Systems, says (on page 68, of the article PEAK TWICE) "If you rest now, you'll allow your body to adapt to the training stress you've put it through so far. The key is rest and avoiding high mileage. If you've been riding all spring/summer, you need shorter, more focused rides, not more miles. The payoff is a stronger, longer season".
During this time of the season I prescribe at least one Anaerobic Capacity (L6), VO2max (L5) and one Lactate Threshold (L4) workout a week. The rest of the workouts are group fun/social rides where the pace is more Tempo oriented. If you're NOT an Ironman Triathlete, I'd keep these fun rides under 2.5 hrs. There is no need to go any further/longer than that. If you do, you're just going to beat yourself up...leaving you open to injury or burnout!