Meaning of “There is not a direct relationship between verb forms and time.”

[sinh]

In the English grammar book "Practical English Usage", the author Michael Swan said:

There is not a direct relationship between verb forms and time. For example, a past verb like went is not only used to talk about past events (e.g. We went to Morocco last January), but also about unreal or uncertain present or future events (e.g. It would be better if we went home now). And present verbs can be used to talk about the future (e.g. I’m seeing Daniel tomorrow). Also, progressive and perfect forms express ideas that are not simply concerned with time – for example continuation, completion, present importance.

Did the author mean by "There is not a direct relationship between verb forms and time" that there is not a one-to-one mapping between verb forms and time (i.e. one and the same verb form can be used to refer to different times)? Or what did the author mean by that sentence?

[Alan]

Yes. The same verb form (e.g. the present progressive) can refer to different times (present or future), etc.