for + period of time

Question

You should write one hour every day.

or

You should write for one hour every day.

Which one of the above sentences is correct? Can someone please help me understand when do we have to use for when talking about time?

Answer 1

To express a duration of time, you use for.

You should write for one hour every day.

You could also use the other option, omitting for, but the meaning may not always be clear in all contexts.

You could omit for in a situation such as:

You should jog 5 hours a day.

When using a sentence such as: You should write one hour every day, it sounds more idiomatic to say You should write an hour a day.

a day or per day can be used in place of every day.