Dr Seiler said in a recent interview that having minimal hr drift was due to staying below lt1. I had already come to tr with a training history of using hr as my main metric, using my promotional code from my stages for joining. Conversational pace was the old rule for most rides and runs so pace was usually set my rpe and measured with hr. I haven’t taken the ftp challenge yet, but i can routinely ride in traditional zone 1 hr up to about 75% of my manually estimated ftp. Doing 1 hour at that ftp setting seems quite hard but it might be possible so my lt1 might be higher percent of my actual 1 hour power.