Reviewing the Meditative subroutines has been a rediscovery, in the past I've tended to add the Ushtrasana to Kapotasana subroutine to the Bow sequence in a backbend focused practice similar to that I was familiar with from Ashtanga Intermediate series, neglecting the other subroutines altogether.
Since practicing Vajrasana at the beginning of the week I've included the subroutine several times at the end of my regular practice in place of padmasana and Vajrasana itself as a posture for my pranayama and meditation practice.
Virasana has turned out to be excellent preparation for the work I've been doing recently on Samakonasana as it loosens and lengthens the quadriceps, it's also an excellent counter posture for any asana like Samakonasana but also badha konasana where the femur heads are rotated outwards as in Vajrasana the joint is rotated inwards, towards each other, I struggle to think of another asana that does this.
It was always a surprise to me that a sequence that included Kapotasana should be called meditative and yet Dharana, the sixth limb of Patanjali's yoga, is Concentration and few postures so readily concentrate the mind as Kapotasana. However it is the vajrasana and virasana postures that give the sequence it's name, both are considered by ramaswami as suitable for pranayama and meditation practice.
Where to practice Meditative subroutines.
The camel walk subroutine strikes me as a nice, stand alone, 'extra' practice, perhaps when you have limited time to practice, although a little preparation would most likely be necessary for the advanced version, perhaps one of the bow subroutines.
The Vajrasana, Virasana and Simhasana are ideal for the end of practice, winding down subroutines.
Vajrasana is an excellent quadriceps strengthening subroutine, regular inclusion will help prepare you for many of the back bending postures subroutines as strong legs take stress off the lower back.
Virasana with it's internal rotation of the femur heads in the hip joints is an ideal counter posture for hip openers, like the leg behind head postures in Asymmetric or any of the Konasana subroutines, especially those in the Seated sequence.
One thing the Meditative subroutines lack is twisting, Bharadwajasana from Day 33 comes to mind as an additional posture, leading into Mahabandha for bandha focus but perhaps a stronger focus on the twisting postures in the tadasana subroutine might make for a more balanced practice.