I have a pretty basic question, I guess, but I've never managed to actually figure it out.
Is it better on your friendship level to outright deny a villagers request or to accept it and fail it?
I work full time and have two small children, I don't have time to find marshal a super rare fish, but I don't want our friendship to lower either. My friendship levels raise super slowly because I don't have the time to send letters everyday, so I don't want to do anything to jeopardize the friendship at all.
I'm pretty sure denying will have a neutral effect while accepting and failing to complete will lower your friendship levels. This is what I've read when researching how to get villagers to move out but it's difficult to know for certain since they don't tell you what level you are on.
I don't really know. I think if you accept a delivery request and open the present or fail to deliver it, then you lower the friendship, but I'm not sure it's the same with other tasks. It's usually best to just deny a request if you don't want to do it anyway since having the "What did you want?" prompt at the top when you talk to a villager is annoying.
I always agreed and then failed the requests(except for fruit) in a town I slowly cycled through. They didn't stop giving me birthday set items on my bday (allll the bdays-I TTed through 2050) so I think that means I still had high friendship ratings with them. I didn't want to effect their originality since I was only keeping them temporarily while I developed the town. (and collected a ridiculous amount of bday items)
I've always accepted requests and frequently forgotten or otherwise been unable to complete them. I've never noticed any observable impact of this on my villager friendships, (even though i've heard it has negative impact). iirc time travelling cancels all pending unsatisfied requests-- that may be a work-around for you.
I think if you deny a request it won't have any effect on the friendship, but if you accept and do the task that the villager asked you it highers the friendship. Not too sure about if you accept the request and don't do it though.