I don't know why, but sometimes as I read stories, they seem to escalate to levels beyond what I'm willing to suspend my disbelief for. Sometimes when reading a story, I get to a point where I just can no longer stand to read the story.
An opposing family is super rich and has infinite resources and leads. Another is a mafia style family and is killing collateral supporting cast, and the main characters are mostly clueless about it. Suddenly, the wrong people are too far away, bombs are being set in the house, a ninja breaks in, and the main character is getting set up for a crime he didn't commit, and there are relationship troubles to boot!
Somehow, having all that happen at once is just too much, and a perfectly good story is suddenly a wallbanger. This recently happened as I was reading what before the breaking point was one of the best Ranma 1/2 fanfictions, Careful Destiny.
Reading as far as I did, to the last written chapter, I can see why the author could no longer write for that story. It just reached a point of no return, and short of going back and fixing it, there was nothing he could do.
Alea iacta est. The die was cast. This is the biggest problem with publishing online. People see what you already put up, and unless you can allow yourself to rewrite, if you reach the wallbang moment, you are pretty much SOL. You lose your readers. Now, this can happen in print published materials as well, but there is usually so much refinement going on there, and a completed story, that either a wallbang moment is written out, or the reader muscles through it, since they know they have a definite end approaching.
So how can this be avoided while still increasing tension? I say limit what is causing tension down to one main issue and a small problem. Solve small problems on the way to solving a bigger problem. Maybe not all problems are solved, and are put off for later (allowing for sequels, or for a payoff down the line), but throwing too many problems at once without it being a proper climactic point in a story is too much, and even then it might overwhelm the reader.
I think people should look at their favorite tv shows and write out the plot. Follow the rising action, the falling action, the plot threads, the hints leading to other things. Write it out, as if you were recreating the manuscript from viewing the show. Now read through it and identify what is going on with a critical eye.
I've done this to a few genres and I've found myself improve each time. It is highly recommended.