Can we use both would have and would in non conditional past statements? For example:
Last year during the summer, I would go home on weekends. past habitual
Last year during the summer, I would have gone home on weekends.
Last year during the summer, I would have completed three projects every month.
What are the differences between these usages? And how to differentiate if it's conditional or not?
Best Answer
As OP correctly says, past habitual - he usually/always went home on weekends. No problem.
As TimLymington says, native speakers might be tempted to interpret this as an incomplete statement, with the unstated continuation "...but because of [some excuse] I didn't". But that's only because we're struggling to find any way to make sense of a rather unlikely utterance, so I suggest we consider a simpler one...
Again, it's possible there's an unstated "...but my wife wouldn't let me."
But if the speaker had just been asked "Where were you last Friday night?", it would be a perfectly normal and complete reply. In such a context, the speaker may be implying that he's normally in the pub on Friday nights, so he would have been there on that particular occasion. Or he may be implying that although he's not absolutely certain, it would turn out that he was there, if the matter were to be investigated more thoroughly.
This one somewhat complicates the issue, because three projects every month automatically creates a past habitual context. Native speakers don't feel tempted to assume there's an unspoken "...if I hadn't lazed around the pool every day.", though they might expect a follow-on along the lines of "but I think I could only manage two projects a month this year."
The fact of the matter is that whatever the textbooks say, people often use would have [verbed] in that way. Semantically, there's no real difference between OP's version and...
...or indeed...
As pointed out, these are not good examples for getting to grips with usage of would [have], because phrases like during the summer and three projects every month blur the focus on exactly what time we're talking about, and what exactly might have been habitually repeated.