I don't really have time to do the prone-to-supine stuff. This isn't residency... time is money.
With a gastroc, you're almost always doing something else too (bunion, flat foot, TMA, whatever).
I just do medial approach mini-open gastroc, frog leg (supine). About a hand-and-a-half (10-15cm) above the Achilles insert, incision over medial border edge of aponeurosis. You can see it on fit people... palpate/guess of bigger folk.
I saw it done that way on a few of my good clerkships and some of my residency attendings, and it made the most sense to me. It's really easy that way... you can typically do it anywhere from 10cm prox to calc insert up to gastroc muscle (but more proximal is more to cut and more chance of sural inj). It's about a 2-3cm incision, usually one aponeurosis stitch, one subcutic stitch, a few subcutaneous nylons. 10min or less.
You identify the gastroc aponeurosis right below adipose, blunt or finger dissect deep and superficail to the aponeurosis.
Basic Strayer cut with straight mayo scissor (or 15 blade with malleable in front of it if you want), assist dorsiflex to feel the release.
It ends up being the same thing as the ACFAS surgical procedures vid "Gastrocnemius Recession Distal" by Al Ng... except a lot smaller incision and frog leg - not prone. It's also the same result as EGR - except it's usually a bit faster and you don't have problems getting it released or the cost.
I usually go a tad distal, but you get the idea in this pic:
...EGR is not bad, but I can do my mini-open by the time the camera equipment is set up and whited out... and sometimes that cam/tube/hook knife equipment falters - or some facilities don't have EGR stuff or don't like the costs. I also don't like the multiple swipes with the baby blade that you usually need for EPF and EGR... not efficient or ideal imo.
...If I'm doing it for bad/neglected/contracted
Achilles rupture repair, then I do open 'V' gastroc... up high right below gastroc heads muscle (as far from rupture as possible), through same incision as the Achilles repair (medial to midline... usually cut soleus a bit too for more length, if needed.