Generating Japanese is slower than English (it's annoying on GPT-4), that's my reason to prefer English sometimes (especially for tech topics). ChatGPT web users don't pay for each token, but API users pay for each token, so they would make different decision.
In my experience, while "continue" can work, "続けて" doesn't. At least not when making it rewrite large texts, which is when I hit the limit. With "continue", it continues rewriting. With "続けて", it tends to make up new text, that yes, is the continuation of what it was writing, but with no connection to the original text it was in the middle of rewriting.
Generating Japanese is slower than English (it's annoying on GPT-4), that's my reason to prefer English sometimes (especially for tech topics). ChatGPT web users don't pay for each token, but API users pay for each token, so they would make different decision.