Fairly new TR. 3 hour long mainly SS intervals per week and a longer endurance ride outdoors the weekend.
Quick question… Has anyone anecdotally or otherwise found extra benefit in pushing interval workouts beyond an hour when time allows eg 75 or 90 mins, ie. do you get more bang for your buck beyond the hour mark for the odd workout than you would do in the first hour. Thanks.
Ive never extended an indoor interval work out myself but I guess you could use ‘Alternates’ to do so.
Yes.
Volumes trumps everything, so extending if you can is very beneficial. Try and do it progressively though.
My interval sessions are often part of a much longer endurance ride. When the weather is nice, I’ll typically do an hour or so of Z2 as warmup (usually riding to a spot that is well suited for intervals), then an hour or so of intervals, then Z2 long ride. I find it very effective and Z2 feels nice and easy after knocking out vo2max work.
This
You can use workout alternates to pick the perfect one when you have extra time.
Joe
I do 75 min rides for more time in zone. 60 min and 75 min workout for me tend to have the same amount of warmup and cool down time, which means as a proportion to the total workout, I get more time in zone with longer workouts.
Hey @barney76,
Welcome to the forum! 
Good question!
Slowly increasing volume over time can be beneficial, but only if you have the time for the extra training, and subsequent recovery that’s needed to absorb the extra training stress.
Each of us has an optimal volume that will remain productive based upon our genetics, available time, and stress levels from daily life. Pushing over that limit will likely only hinder your progress, so it’s important to know where that is and focus on optimizing your training at or below that level.
If you’re feeling good and have the time to bump your prescribed workout from 60 to 75 or even 90 minutes, feel free, but first ensure that doing so won’t affect your next workout. Adding 50% more volume to today’s workout won’t help much if you end up skipping tomorrow’s workout because of it.
Stay on top of fueling, and make sure you’re recovering well between sessions. As a good rule of thumb, if you’re seeing red or yellow days on your TR calendar, now might not be the best time to start adding more stress to your plan. We do have a new tool that helps you figure out when the time is right, though! You can check your recommended volume at any time now using the Check Volume tool. Check it out below if you’re interested.
If you have any other questions about any of this, feel free to reach out! I’d be happy to chat some more. 
My “one hour workouts” tend to be a few hours for the same reason 
Never thought of it like this before but makes perfect sense, more time in zone = more bang for buck with just a little extra time invested.
Hi Eddie, this is super helpful, thanks! It actually suggested I increase one of my hour long hard interval sessions to an hour and a half so will try and do that.