Its definitely worth it, if nothing else its good practice, and identification of your weaker parts (they cover a wide spectrum) would be super useful.
Also, you would be given an option to schedule a practice mock test for the final interview.
For optimizing the top of the funnel, one approach which has worked well for me in the past is to use LinkedIn to connect with EMs who are hiring (they are looking for people like you), friends at other companies & and also accept invites from 3rd party recruiters. Good 3rd party recruiters can specially be helpful in reviewing your profile, and finding good fits. In the past they've helped me discover some very interesting companies. Getting referrals via TeamBlind is common as well.
Also keep in mind that hiring tends to be seasonal. Companies are generally very aggressive at the top of the year, and by Oct-Dec things do slow down a bit (but this is not always the case, for example if a company raised some $$$ in that period). In the past I've avoided applying to postings which are more than 3 weeks old.
You could also try services like TripleByte, which flip the funnel, and help you go directly go to onsites (there are some caveats though).
For the tech rounds, it's just more practice. Unfortunately the interview process is heavily biased towards people who practice, and has little to do with your actual abilities - and you are competing against such folks. For that I've found Pramp, interviewing.io, leetcode, educative (the grokking algorithms and system design courses), GH system design primer, (our even services like Outco.io) etc. to be very useful. The good thing is that atleast in SV these bits have become fairly standardized now, and if you spend time preparing, it significantly increases your hit-rate with everyone.