This practice was not limited to Shuri-te; from the picture displayed above in which Chojun MIYAGI and Juhatsu KYODA exercise in shirtless conditions, it is considered that this practice was common in Okinawa, including Naha-te.
この習慣は首里手に限らず、上掲の写真で宮城長順と許田重発が上半身裸で稽古していることからも、那覇手も含めた沖縄一般の習慣であったのだろう。