I don't think it's helpful for anyone to say 'it takes me this long, so it should take you the same time' - it all depends on a number of factors.
Arguably I've been working on this WIP for seven years. In reality, I got the idea, wrote one chapter, put it down for five years. Then I wrote half of it during November 2012, got burnout, life happened, then wrote the other half in November 2013. I'm just putting the finishing touches on it now, then will do an edit. Has it taken me seven years or more like seven months? I'd argue the latter (nb. during the seven years I have written at least two other full manuscripts).
I know I can write 1k a day fairly regularly. When I've done Nanowrimo I have been able to write more like 2k a day regularly, but it usually leaves me with burnout so bad I can't write at all in Dec and Jan.
You shouldn't use life as an excuse for never writing (ie those people who talk about it but never actually sit at a keyboard and try), but you can, I think, be kind to yourself and realise sometimes it is easier to make the time than during other periods.
For example, when my day job involved writing, I found it hard to do much creative writing. This won't be a problem for some, but for me I just couldn't write 4k-8k of words at work and then do more at home.
However, just to fence sit, it is also important to realise that in most cases you can make time if you really want. I am pregnant and shattered so though I prefer writing at night I've moved it to lunchtimes at work. It's hard to write around children, but it just means you have to make the most of any time you do have.
SOOOOOOO this post has got too long but:
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I've written around four full-length manuscripts. When the going is good I've written and edited them in under a year - it's just I've had some life stuff get in the way and artificially stretched some projects out. If I was doing it fulltime I think I could do two in a year at a push. Or maybe if I just knew I had a contract instead of doing it for fun now and then :)
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In the evenings after I've watched TV and had dinner with my husband, we normally retire to different hobbies - I go on my PC and write; he plays console games. Realistically I often nap/procrastinate/web surf instead, but by sitting down every night I know I have the opportunity to do it - it's down to me if I don't. As I mentioned, recently I've started doing lunchtimes instead as I'm tired in the evenings. Setting out any regular time will benefit you, even if it's only enough time to do 200 words a day.