This Sun Salutation is called the Long Turn Sun Salute because of the way it slowly progresses to the spinal twist called Reverse Triangle.
It is good practice to choose postures that are close to one and other when weaving through them in a flow. It makes transitions effortless. In this sequence the postures flow well together.
Sometimes you will find that some poses prepare you for another. In this case the forward bend with the hands interlocked (Parsvotanassana) really helps the hamstrings open up. This prepares you for (Reverse Triangle). I always perform Reverse Triangle later in a sequence. It is one of these poses that is mentally disturbing for students. The mind feels distressed when it cannot receive oxygen easily. Avoid an uncomfortable experience by bending the front leg slightly.
It is however a little less traumatizing when the body is warmed up a bit and is quite enjoyable for advanced students with flexible hamstrings even early in a sequence.
Reverse Triangle really compliments Warrior 1. It causes the body to face forward correctly and the transition into the pose flows smoothly.
Exhale into Reverse Triangle. The left leg straightens, the right arm comes down
and left arm stretches up. It is also better to place the right arm to the
inside of the left leg and if a block isn't available come onto your fingertips.
(Take a few breaths in this pose if you like.)
Bend the left knee a little if the hamstrings are not very flexible. This will
allow an easier pose and breathing will be better. (Work on flexible hamstrings
Inhale into Warrior 1 Pose.
(If you want the back foot to be flat on your mat try stepping it forward.)
Exhale into Tadasana with the hands in
Perform the same sequence on the opposite leg. If you like
you can vary the headstand sequence each time or simple
perform the same one.