grammar - When to use するほうがいい instead of したほうがいい in order to mean "Should do"?

So, I was in hello talk writing about how eating ramen everyday might not be healthy:

(I will number the sentences)

1 - ...だから、時々ラーメンを食べたほうがいいね

Then, a native speaker corrected my sentence to:

2 - だから、たまにラーメンを食べるほうがいいね

Someone told me in the past that in order to say "I should..." I had to use the pattern 「た+ほうがいい」 is it wrong?

@Goldbrick also helped me in the chat saying that he'd rather say something like:

3 - だからラーメンを食べるのは時どきだけにしたほうがいい

or

4 - だからラーメンは時どき食べるぐらいにしたほうがいい

He, this time used the したほうがいい pattern instead of するほうがいい. But he couldn't exactly explain why's that...

So when should I use するほうがいい and したほうがいい to mean should?

Thanks in advance!

Answer

You were trying to say you shouldn't eat ramen too frequently, right? Then 時々食べたほうがいい is wrong because it recommends to eat ramen to some extent than nothing.

Adverbs don't determine polarity of a sentence in Japanese unlike English. e.g ほとんど殺した means "killed almost everyone", not "almost killed".

In addition, したほうがいい is an advice for a specific or an actual problem. た form represents that something is concrete. When you are fishing and find some shape, you say いる いる… then, once you confirm it as a fish, you say いた. そういうこと means things like that while そういったこと means things including that. That's how they are different.

In this regard, たまに食べるほうがいい is a little better, if not enough, because it's a criteria for a general problem apart from if you actually do or not.

時々だけにしたほうがいい and 時々食べるくらいにしたほうがいい are fine because either part before したほうがいい stands for refraining from eating too much and したほうがいい recommends to carry out that.