But when the squal line extends hundreds of miles, sometimes the only possibilities are to find a good enough hole or turn back (which I have never had to do as yet).
I too, have not heard of a turn back but I am sure there must have been a few.
I did a 180 in a 737 between Fiji and Wallis is. Wallis weather marginal in terms of cloud base but that's all. Cruising to Wallis the front ahead was the widest I had ever seen and real black. Moderate to severe clear air turbulence.
Unable to contact Wallis flight service due they had a radio failure so no weather updates. I approached within 40 miles of this solid cloud but nothing red on radar just a mess of green and yellow which turned out to be rain attenuation. I suspected embedded CB
Got the funny feeling I didn't like this one bit and did a 180 back to Nandi (Fiji) to fight another day. Landed and went to pub. Next day weather fine and reports came in overnight of Wallis runway previously flooded but water now receding. Landed Wallis and saw whole airfield lots of water but runway good. Was then told intense fast moving depression caused 75 knots winds at Wallis and all navaids knocked out including radios. Turning back was a good move after all.