Cura Estimated Print time way off?

Posting this in mini rather then software for us new owners that are also new to printing. Keep it all in one spot. Not a big deal but I have noticed the estimated print times Cura gives for a model is not so good? Last print gave me 3hrs and 43 mins but ended up being closer to 7hrs. I would imagine the material used may be off too?

I have found this to be the an issue in Slic3r & Pronterface as well.

I almost always double the “estimated time”.

Should add that I have a TAZ4.

I found this was an issue but then I changed the acceleration on the machine from the preset 500 to 900 and now the estimated time is a lot closer, but still off.