On the 8th of september I registered on Xert and uploaded 3 months of rides. I was just curious, I don’t aim for any real event. There’s one climb that I really like 6km from my flat so I chose an athlete type of climber (10min W/kg), an improvement rate of moderate-2 and a target date of the 8th of november (8 weeks later). Xert guessed that I could move my TP from 245W to 275W. Honestly that sounded like absolute bullshit to me.
I then just tried to keep the training deficit or surplus low just using my daily commute and some weekend rides. I got sick one week so I moved the target date one week and I took some “rest days” when I felt like I did not want to ride without changing the target date this time.
A few weeks ago I did my climb, aimed for my supposed 20 minutes power of (then) 296W, missed it by 9 watts for 17 minutes… And ran out of climb. That’s 30W more than what I ever done there and I actually had a bit of strength left (a tiny bit, I think Xert is a bit optimistic. I don’t care as long as it is consistent and not too far from reality)
The target date in Xert is tomorrow. I hit a breakthrought today, coming home from work, and the calculated TP is 281W. 
This forum is mainly used for support, so it’s the questions, difficulties and problems that are discussed. But Xert worked for me absolutely brillantly!
The most important thing in Xert is the automatic fitness signature recalculation. By far. That allows me to stay motivated and measure the improvement easily when coming from works, even when I have to dodge a car, take care at crossings or freewheel on a short decent. Instead of scheduling a ludicrously uncomfortable test every few weeks, spending the weeks between test without knowing if I’m improving or not, and then risking screwing up the test, I just try to blew my legs off while coming from work. If I cannot get a breakthrought on tuesday because of the rain or on wednesday because of a tractor I’ll get it in on thursday or friday.
And then on saturday and sunday I’ll ride at a relaxed and calm pace that’s as fast as my maximum of two months ago. Or maybe I’ll try to go fast?