Oops – left this as a draft from awhile back. 
I had a similar opinion of base phase the first time I completed a phased progression in Xert, but the results were very positive compared to other platforms I have used.
Base should be low intensity with Xert’s hybrid polarized approach. That’s why it works well for most riders.
It is normal to carry a slight deficit. Any rest day (or deficit) is absorbed into the rolling week moving forward.
Your goal is 11am-1pm position on the needle but it can waver depending how you allocate your weekly hours.
It is up to you to decide on easy, rest, long, and hard days. If you follow a consistent pattern XATA will recommend similar workouts the following week.
Most users don’t start at Aggressive-1 but the point is you can dial IR up/down depending how you respond to the prescribed TL over the phased progression.
Most users with an Aggressive IR would be taking a rest week at some point and during that week dial IR down.
When you select higher ramp rates you are increasing both time commitment and intensity.
As @wescaine mentions “as your TL goes up, so will the required hours to keep maintaining the aggressive improvement rate”.
I realize you are many days in with plenty of experience now, but you may pick up some pointers in this post –
Beginner questions - Support - Xert Community Forum (xertonline.com)
I am about three weeks away from my first TED this year, still completing all recommended workouts at 100%. However, I am not feeling as eager to toss in a BT workout like I did while in Base and Build. I’ll wait and see how Peak finishes out to compare the prediction.