With reference to this grammar site which shows the different scenarios the simple present is used:
http://www.englishpage.com/verbpage/simplepresent.html
Classified under USE 4 include:
I am happy.
It is here.
He knows it.
While USE 1 is of repetitive action.
John uses that shaver (often).
Now for the following sentences there are 2 verbs, so is it USE 1 or 4?
That shaver is used.
It is used often. (Should it be USE 1 since "It is" and there couldn't be a repetitive action of "is used")
http://www.englishpage.com/verbpage/simplepresent.html
Classified under USE 4 include:
I am happy.
It is here.
He knows it.
While USE 1 is of repetitive action.
John uses that shaver (often).
Now for the following sentences there are 2 verbs, so is it USE 1 or 4?
That shaver is used.
It is used often. (Should it be USE 1 since "It is" and there couldn't be a repetitive action of "is used")
Comments
It is used often. [USE 1]...the verb here is use in the passive voice (is used). And it denotes a repetitive action.
In that case does 'is' denote the current/prevailing manner of being? i.e. 'It is used often' means presently being in a way that the action 'use' happens frequently upon.
Wait for others' opinions.
He is often moody.
Does the adverb describe the adjective or the verb 'is'?
The previous sentence (It is used often), however, has the verb 'use' in the passive voice 'is used'. It is true that participles (present or past) such as boring and bored function more as adjectives than verbs (the verb be becoming the main verb of the sentence). But a verb in the passive voice 'be + Vpp' should be treated as a single verb. In some languages like Latin and some Asian languages, the passive voice of the verb is not formed by using the auxiliary verb be. It is formed by simple inflection of the root verb.
e.g.
Ninakaw ni Juan ang panyo. (The hanky was stolen by Juan)
Nagnakaw si Juan ng panyo. (Juan stole a hanky)
or
poemam legit (He reads a poem)
poema legitur (A poem is read)
Thus, I wouldn't think of the verb 'is' as the main verb of the sentence in question. I would think of it as a part of the verbal phrase 'is used'.
You can also look at it this way. The verb 'be' can be used as an auxiliary verb. When used as an auxiliary verb, be is followed by the present and past particple forms of the main verb. e.g. He is using the knife (now). or The knife is used (very often). An auxiliary verb is not the main verb in a sentence. It is just a part of the verb phrase. Has in He has gone is just a part of the verb phrase has gone. And to the bank in He has gone to the bank doesn't describe the auxiliary verb has but the whole verb phrase has gone or simply the verb go (in the present perfect simple tense).
-Lagataw
--X----X----X--|--X----X----X-- where X = 'be + Vpp"
Now
I wouldn't agree with you on the case of present perfect.
He has often gone there in the past - adverb 'often' is on main verb 'gone', 'has' is not included. 'Has gone' is not treated as a single verb like the simple present passive.
And adverb placement is irregular:
It has often been.. vs. It is often..
There's no such syntax as 'It has been often' is there? It sounds wrong.
But not all passive (be + Vpp) are of repetition (USE 1 as shown on the grammar site). Some verbs are inherently continuous for instance 'know' and 'maintain' in simple present.
Someone knows about it ----> It is known ("Knows" & 'is known' seems to be USE 4)
In this way 'is known' is just like the 'is + adjective' i.e. both are USE 4 and 'is' continuous. Am I correct?