Hi! I’ll write one post to cover two questions which trouble me.

First one is about Training Advisor, and, precisely, the “as of” expression.

My “advice” time is set at 15:00. Today is Friday, so now - before 15:00 - it says that my training deficit/surplus as of friday, 15:00 is XYZ, and “Sustaining this improvement rate will require about 13.3 hours of training per week based on your recent training history that includes outdoor and virtual activities and workouts performed on Fridays as of *1:00 pm”.

And here is the tough part: after friday, 15:00 it won’t show me “as of saturday, 15:00”, but still “friday, 15:00”.

So during one day I’m receiving info about future, and after that time - about past.

My question is: how to interprete it? I’m trying to “decode” it as follows, but am I right?

• [when the time is in the future] At 15:00 today my deficit/surplus will be at level XYZ.
• [when the time is in the past] At 15:00 earlier today my deficit/surplus has been at level XYZ.

The second question is about breakthroughs: if my FTP has dropped significantly (because I was sick, or performing non over-FTP-rides) - would the FTP be set as close as possible to my real FTP after one breakthrough, or should there be performed more than one?

I mean, for example:
a) FTP: 200 W ---- whoa, you’ve made an great effort -----> FTP: 340 W
b) FTP: 200 W – ok, a great effort – 230 W – whoa, another – 250 W – oh, yet another – 270 W

Your calculated form is in a constant state of flux based upon what you have done recently, how much strain it entailed (duration + intensity), and how much time has elapsed.
Many of us leave As Of time set to the default of 11:59pm to reflect advice/status as of the end of today if no training occurs today. Or you could set to 1:00am to reflect the start of today.
Those who train regularly at the same time each day may set that as their As Of time.
It’s used as a reference point for your training advice today or in the future.
You could, for example, complete your training today, view the Planner, select tomorrow’s date, Show Workouts, and recommendations will be based on your As Of setting. Change the As Of time shown to a different time and the recommended list will recast when you tab off that field or select Show Workouts if viewing on a phone.
In practice the list results may not change much or at all because calculated form remains the same between the two times. Listings will change, however, if you are on the cusp of moving from tired to fresh form later in the day.

Be aware the deficit/surplus is a relative number to consider. Although calculated to show pts below/above Noon position on the Training Pacer, it’s not an exact number you must heed.
It’s the value to return to Noon position (neutral) vs dipping toward red (Falling Behind) or riding more and getting Ahead of Plan. Your main goal is to keep the needle in the 11am-1pm position to attain/maintain your currently selected IR (improvement rate). That position may vary over the week (or week to week) as your schedule permits.
The Pacer Needle reflects a moving weighted average over a rolling 7 days. This is a significant difference between Xert and platforms based on targeted TSS tables. There is a flexible ebb and flow nature to Xert. You can also change the flow rate to accommodate changes in your schedule and ability to train more or less hours week to week.

BTs efforts will zero in on your fitness signature over time if not present in your recent historical data. You can force the issue at any time by searching the Workout Library for “fitness test”, select one, and ride it in Slope mode using gears/cadence to hit or exceed targets when able. You can also stand up on any intervals designed to push you to failure and try to sprint for at least 5-7 secs before you collapse.
The goal is to demonstrate your ability to perform maximal efforts under fatigue.

Signature values in Xert are designed to fluctuate dependent on daily activities and changes in training load. Once you’ve established a viable ballpark signature you can also adjust the Decay Setting in Xert to reflect how signature decay occurs. For example, you could set to No Decay/TL Matched for an extended base period where you don’t expect to challenge yourself often. Or leave at Optimal Decay if you frequently hit max efforts during hard group rides or races on Zwift.

Lots of newbie tips posted here – Beginner questions
Academy series videos are the quickest way to get up to speed – Discover + Improve + Perform
FAQs here – Support Home – Xert

Welcome aboard.

I think your understanding is correct.

To see tomorrow (or any other day) you can look at the planner, for info

You want your signature as accurate as possible at all times so if you can achieve a) you should. There is no point in low-balling your threshold. If you follow the path of b) that’s also fine if those BTs are always ‘all out’ and to failure.