“straight/straight ahead/straight on” - for native English speakers.
When talking about directions, I’m not sure when you would use
“straight”
“straight ahead” and
“straight on”.

If you're at a crossroads, for instance, can you then say “let’s continue straight” or do you have to say “continue straight on/ahead”?

Thanks for your help!

Question

“straight/straight ahead/straight on” - for native English speakers.
When talking about directions, I’m not sure when you would use
“straight”
“straight ahead” and 
“straight on”.

If you're at a crossroads, for instance,  can you then say “let’s continue straight” or do you have to say “continue straight on/ahead”?

Thanks for your help!

Answer

American here.  I generally just say "go straight" or "keep straight."  Occasionally I get wordy and say "keep going straight."  :)  We sometimes do say "straight ahead" but we tend to use that when you're nearly at the destination: "go straight ahead and the store is on your right."  To me, "straight ahead" implies that you only have to travel a short-ish distance.

"Straight on" and "continue on" are not as common here in America, but I think they are more common in the UK.

Answer

Thanks Chris.

Answer

BTW, we'd be unlikely to say the "then" in your question.  "Then" usually implies a sequence of events instead of a location in time: "He ate, and then he slept."

Answer

Thanks Linda.

Answer

None is incorrect. Anyone would understand any of these phrases meaning "No turn at this point". "Straight on" may be a little more likely in the UK than the USA.