There are more people than you'd expect who can talk the talk but can't code at the same level. In the majority of companies, I'd bet there aren't too many openings for engineers in such a narrow role. If you don't want to work with an 'idea person', would you want to work with an 'idea engineer'?
Multi-day interviews are likely overkill, but a full day interview is completely fair. There's no need to do 4 back-to-back algorithm whiteboarding sessions, but testing other aspects such as data modelling, general architecture, and coding style/ability are all high-signal.
Multiple days? Not a chance.
If you were paying 2x rates or real equity, ya I'd slog through a day long interview, but I bet you aren't.
What does your company have to offer that would compel me to spend 8 hours interviewing that another company doesn't?
Something that's worked well for me in the past is to secure at least 1 good offer - compensation you feel comfortable with, recognizable brand, but still an offer you're willing to walk away from - and then give notice.
Then, after leaving, spend additional time (up to 4 weeks) interviewing with all the other companies you want to. Keep in mind that many companies offer a sign-on bonus, and using it to cover this in-between time is high-return, likely more so than buying a new car/vacation/entertainment system.
You can be upfront about this break in your interview loops - "I'm no longer working at company X, but I have a very competitive offer from company Y and considering several other ones." There's no guarantee you'll be able to keep all the offers you receive (many of them will explode), but you should have a steady pipeline.
Whenever you feel comfortable, you can exit the pipeline, and begin negotiation with the outstanding offers you have. Last I did this, I went onsite ~15 times among even more interview loops.
I have a hard time taking seriously a company that doesn't give me 25 days in EU. (better be with 25 sick days :D).
Make a 1h test, NO fancy problems, just the basics. Think: summing some numbers, displaying some stuff on the console.
That doesn't substitute to the on site but it goes before to ensure a minimum level and some screening.
It's win-win for everyone. It's efficient and straightforward. On the top side, it's easier for the candidate to take 1h whenever he wants than to schedule a full phone call that will ruin half a day for both of you.
Every founder thinks their company is great. People who want jobs will happily reinforce that delusion to get the job. Some companies are better than others, but most of it is really boring stuff. I guarantee that everyone working at your company is there because they need a job.
It's not even about being attractive to juniors, seniors or mid level. It's just looking for desperate, even if you have a brand name.
Screw the rest, seriously, it's just not worth the trouble.
A couple of weeks back I saw a repo on Github. Preparing for an interview @ Google. It was a mile long. Never doing that.
