Well, I think we all have moments when we are working on a serious project, a tiny spark ignites in your head. Like a blister on your feet, at first, the symptoms are small, but overtime, they reach a size so big you can't even control yourself. And what do you do? You open that Microsoft Word document--the one that's fresh, new, and blank. Won't be blank for long, since you're punching those keys with your fingers. Soon, you have 1.2k worh of words, more than you'd written that day for your "serious" project; your supposed number one priority.
Now not everyone struggles with this, but both my sister and I do. One moment, I'm writing something I think is going well, the next, my sister tells me what she's up to and I am suddenly inspired by some new idea. Some ideas are usually not better, however.
Now I'm no expert at giving advice, let alone WRITING advice, but here are my two cents jus in case there are those who have this problem like we do:
I believe there are pros and cons when it comes to a million SNIs in your hands. Leaving a WIP for a new SNI is a very risky thing to do (of course, you can always returnto your previous WIP, but it might be difficult to get the feel of that WIP back). On the other hand, you should try to see how the SNI works out because you never know, it might be the one. Also, I never believe writig something that doesn't work out is a waste of time; it's practice to help you get better.
Having too many WIPs and SNIs can confuse you, so it might be best to keep a couple, maybe three or four at the most. But having a lot of SNIs can also be a good thing. If you are not taking one of the SNIs seriously, try to steal a scene/idea/quote/etc. From it and try to incorporate it into your main WIP.
I always write my SNIs to get them ot of my head. Sometimes they don't. Sometimes they actualy stick around and become my main WIP, so I would recommend writing down your SNIs whether to wash them away from your system or just to see whether it works.
However, the most difficult part about having so many SNIs and WIPs is figuring out which one to write at what time. The answer can be as simple as, "write the one you feel like writing". But I struggle with picking which one because I get excited over every one, and if I could, I'd write all of them at once.
The best way to go by this is to write the WIP or SNI you believe in the most, which in a sense, the WIP or SNI you are feeling.
So these are the procedures I follow when in doubt of which WIP or SNI to write. When in doubt, do not panic, just write what you want and feel like. Maybe overtime, one of your new SNIs become your number one priority when it comes to writing.