This has been previously discussed on multiple occasions here in the forum and mentioned on the podcast as well. The plan notes already mention that you can replace a weekend SS ride with a longer endurance variant if you would like. You could also do a LV plan if you’re doing a higher volume plan and use the extra time to add in long weekend rides, condensing your TR workouts into the week. Here’s some of the other discussions on that that come up if you search the forum if you’d like to see what people have said in the past:
There’s been some discussion about when Plan Builder will and won’t prompt you to recalculate in the Plan Builder announcement thread, and I believe it ultimately depends on the priority of the event and when you added it. I’m not sure on the exact scenarios when it does and does not prompt for a recalculation, so hopefully someone else might be able to address that more specifically. You can manually adjust volume after the fact on a block by block basis, but that isn’t determined based on event length AFAIK. To your last question, I do recall that adding an event after your last A event will not force a recalculation prompt. You would need to remove the plan and run through Plan Builder again to have it account for that event.