[takinola]

It's counter-intuitive but the best time to get a new job is when you are happy at your current job. Most people think "well, things are going great. Why should I look for another job?". It's pretty simple. Ask yourself the question "What offer would make you change jobs?". Most people start searching for jobs when they are unhappy with their current situation. If your job is crappy, then you will take pretty much any offer just to get out. If things are going great at your current job, then the only thing that would make you move is a fantastic offer. Why wait until things go sour then move on to another sub-optimal situation? Why not use the time to find a fantastic offer now?

[gombosg]

This makes sense, although having a great and a crappy job is a wide scale, with most people probably being in between somewhere. And switching jobs is not just about offers.

In my experience, looking for a (good) job takes a lot of time and energy, and OP's experience reflects this well: you do have a lot of calls, emails, interviews etc. that lead nowhere.

You may do the onsite interview to learn that their pay range is way off or that the office is just not a good workplace physically.

Even if everything looks nice in the benefits package, you can end up having a bad manager, teammates or too chaotic/boring/legacy/complex/(insert your nightmares here) projects - these are risks that you take on with any job switch, not just the risk of the job search itself.

[takinola]

Nothing comes for free. You're digging for jobs with the hope that it turns up a diamond sometime along the way. It's tasking but the only question is if the possible payout is worth it to you.