On-line presence: is it a waste of time?

I'm currently in the process of sorting out my on-line presence and it is a bit of a nightmare! I've written a list of all the sites I need to post to, update etc. and the current total is:
- Facebook page
- Twitter account
- 1 websites
- 2 blogs
- 14 networks, galleries etc.
This is just my art stuff and doesn't include both my day jobs ( fb account and a second page, another twitter account, 2 more blogs, website and shop front!). It sounds like a lot - but there are actually loads of others I have contemplated but so far resisted! If all of these were productive the time spent updating etc. would be worthwhile but I am not convinced that this is the case and currently have no method of evaluating it?
One of my day jobs is studio-sweepings which is a fairly recent thing (not sure how long the other day job will continue and needed an alternative source of income). Almost 3 months ago I began to sell on notonthehighstreet. It involved a one off registration fee which was a bit scary but was the best thing I could have done - early days but a steady stream of orders (and a brilliantly well organised, effective, supportive company) means I should be able to earn a reasonable income over time. The time spent on 1 facebook page, 1 twitter account, 1 blog and noths shop front maintenance is measurably productive and worthwhile in terms of income received.
This has focused me on how I can measure the productivity of my online art stuff. Obviously the aims are different  (I do the day jobs so I can make the work I want to without compromising) and income is not a priority (although I'm don't object to selling it!) so evaluating it is trickier. Someone once said to me that you don't have to sell work to be an artist but you do have to exhibit and I think I agree with that - it is important to me that my work is seen and responded to. It seems, for me, there are a number of reasons for being online - to promote myself, my work and my exhibitions, to network & socialise, to hear about and participate in events, exhibitions and opportunities, to be informed about what other artists, galleries etc. are doing, to document, discuss and to sell. The first step is, I think, to go through all of the above sites and work out exactly what I am hoping to achieve from them, how much time they take and then try to work out how to evaluate and measure if they are successful (and also if they are worthwhile continuing with). The second thing I want to do is to link as many sites as possible so that I don't have to go to each site to input identical information. I have made a start by linking blog, twitter and fb page but I also have high hopes of Smish (image above) which promises to implement even more integration and also make it easier to have a visual overview (pictures instead of a written list :)) Fingers crossed it's as good as it sounds. Until this is done I shall steadfastly resist adding more on-line content or maybe a 'ditch one before you add one' attitude may be the answer?