No, it’s really hard NOT to do mentally, but if you listen to the podcast they strongly advise against doing this.
Basically the premise is that if you chase average power in a SS session, you potentially end up doing a lot of time outside of the SS zone…as you describe. Say, for instance your FTP is 300, and your workout is 3x15min at 270 (90%). You get through the first 5 minutes at 270, then come up on a stop sign…you gotta coast up to it, slow down to 8mph, look both ways and coast through, then get back on the gas. Look down and your average power is now 255. In order to get it back to 270, you increase your power to 300 for the next 3 minutes and it slowly creeps back to 270…then you fall back to doing 270. Because of this surge, 270 feels a lot harder than it was before and you spend the last 5 minutes of the interval barely holding on to 270. Or maybe you hit another stop sign/light and this cycle happens again. Now instead of doing a sweet spot interval, you did a mild over/under interval that taxed different systems which may not be quite as repeatable the next day.
I believe the best advice is to a) find a better section of road that you can do the full, consistent interval on without interruption…and/or b) disregard average power completely and only focus on hitting the target power in a given moment. You can even edit your bike computer screen so it doesn’t show average lap power if you can’t avoid the temptation to chase it. If you have to stop pedaling or slow down for something or do a sharp turn or little downhill or whatever that causes you to not pedal, that’s okay. Get back on the gas as soon as you can, and go right back to hitting the target power, but not above. It’s slightly less perfect for muscular endurance than riding inside and having to pedal constantly for the entire duration, but it’s better than turning a SS workout into something that it’s not.