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For Outside Workouts, this is common – especially for Endurance workouts.
Many Endurance workouts are divided into intervals for Inside Workouts to break them into more manageable chunks. For a lot of athletes (myself included!), it’s mentally easier to break the workout down into smaller pieces and focus on getting through one interval at a time until the workout is complete. It can be challenging on the mind to see a countdown timer for a very long interval – especially if you’re doing a Zone 2 ride on the trainer that lasts multiple hours.
When it comes to riding outdoors, however, that’s usually less of an issue. Since we’re physically moving through our environment, there’s a lot more stimulation we can focus on (and should focus on so we’re safe!). It’s simpler for athletes to follow along to an Endurance workout that uses a wide percentage of Zone 2 as their power target when riding on the open road with traffic, stop signs, varied terrain, etc.
Hope that clears things up – feel free to let me know if you have any other questions!