A couple things to consider –
Your Power Duration Curve in Xert is actually a combination of theoretical and actual power performed. IOW under the ideal conditions your performance under pressure indicates you could achieve indicated values on your curve.
Peak Power, for example. is typically power meter based but that value can get bumped up from a max effort expressed during MPA drawdown where you are well below your 1sec power.
The primary component to signature validation is measuring your performance under fatigue.
This article best explains the ways signature values are extracted during activities and why a paced effort like a RAMP or 20-minute test isn’t required.
Breaking Through the Xert Way! – Xert (baronbiosys.com)
Also note with the latest signature algorithm updates (Nov 2023) suggest leaving the decay setting at Optimal for best results. Signature adjustments will occur without frequent BT events.
As far as BTs go, you are just as likely to generate one on a tough workout, ride, or virtual race that includes moments of maximal efforts under fatigue.
See this topic for a variety of examples – Let’s See Your BREAKTHROUGHS! 
- General - Xert Community Forum (xertonline.com)
With EBC Android there is the option to ride a workout, end it, select another, and keep riding to record multiple workouts as one activity. OTOH there is nothing wrong with multiple activities to reach a particular XSS goal for the day.