I feel this too for many of my sites. I have a different approach to each campaign that I am running and have written a pretty complex schedule to handle all the daily, weekly, monthly tasks that I need to accomplish for each one.
Recently, I have gotten extremely excited about a particular niche authority site that I created back in early December last year. It is an Amazon affiliate site with just 11 pages of content to drive targeted traffic to the site. In addition to this, are the 38 affiliate product review posts that I have on here. Since the niche is somewhat seasonal, it is now starting to roller coaster out of control. I have seen some interesting impressions for search terms that I was not originally targeting and I am now in the process of creating new content that is specifically targeted towards those new keywords.
Several of the pages on the site are on Google pg 1 search results and climbing every day. They often outrank both Amazon as well as the manufacturer's page for those particular products! This has actually leveraged a position with many of these manufacturers allowing me to add reciprocal links. I am now becoming a true authority in this niche and my original content (all reviews are around 550-600 word articles written by me) is getting linked to from my visitors.
When I created this website, I had actually put some thin content on there just to have something and pretty much placed this on the back burner as I had too many other projects that I was focused on. Now that those other campaigns are working on autopilot (minus the backlinking strategies), it has given me a chance to go through all of my site pages and SEO optimize them.
I am extremely proud of what I have created with this one particular site and I plan to undergo a major theme update in the future with some fancy graphics and a polished look to it. While my IM income is spread out over several dozen different campaigns (Adsense MNS, CB and other CPA offers, Amazon, eBay, etc), I am getting the feeling that this one particular site is going to surpass the combined income from all those other projects!
I have not had a full-time job since October last year and have turned this into my career after having done IM on the side for several years now. I am already in the works on several other Amazon affiliate projects now and should start seeing earnings in the realm of $2500/mo. from my biggest site.
Keep at it every day, make a plan and stick to it. For those of you reading this that have yet to experience the excitement that a single campaign can bring or have yet to start a website and earn that first Adsense buck, get out there and take action!
Remember, "you'll never know where you stand in life if you keep sitting!"