You go into this process knowing that it consumes time and that not everything is going to pan out. If you had the data and processes to identify the perfect candidate, you wouldn't need to bring people in to interview.
It's not waste, it's data collection. If you're not building usable data out of your interview process, your hiring process sucks.
My team was interviewing candidates recently and we brought in a guy that was great on paper and in the interview but we had other candidates scheduled and two of them ended up blowing the first guy away. I'm glad we delayed that hiring decision until we had an appropriate amount of data.
Also, think of it like dating (or any other matching market). Being outcome-dependent says nothing about your candidates but a lot (that's unattractive) about you.
The best way to do things is to build good relationships. Your company and your developers should have a network of people you can bring in at any time to interview for a position. As a developer you should also have a network of contacts to know who needs developers. Instead you're waiting till you're desperate and coming off as needy. If I see that, I'm going to ask for a lot more money or as an employer offer less.
Thankfully for my wallet, almost everyone else is in the same boat as you.
...and if I'm out interviewing for fun and find a better fit, I'm probably going to take it.