Do I really have to make a custom cover letter for each job application or can I just use a template and make a few tweaks here and there?
Yes, you should create a custom cover letter for each job application. A canned letter is very easy to decipher - recruiters see a lot of them, so they know the difference.
The letter should be centered around the opportunity you are applying for, and answer the following questions:
Your answers will probably vary depending on the position for which you're applying, so custom is the way to go - it will show you are very interested and excited about the opportunity and highlight the most relevant qualifications you have for that particular opportunity.
SoFi's Career Services Team
No, I don't recommend submitting a cover letter to every job you apply to. To be economical with your time, since it is a numbers game, you need to maximize your time on applications which are interesting, feasible, and that you would actually work and do. There's reach and then there's desperate. Keep chugging along, and keep a good pace.
I've gotten my last two jobs as contractor, one for 9 months via careerbuilder.com (took about 1-2 months lead time) and the other is ongoing but expected to be 6 months then full-time role (via Linkedin.com and I was a premium user with 10 "fishing line" optimized searches concurrently running)
The people who say they want customized cover letters don't realize how taxing it is on the person who is slogging through dozens of job applications on the daily. In reality, they should be put a little effort into the resume and followup instead. Most cover letters are replaced by a good statement or look into one's linkedin