For grad school application (US univerisity), we need recommendation from prof. I guess the process is that system send out recommendation letter request to prof's email.
Do you guys know how long does it take to submit these recomendation letter? Does it need to fill extra form while submitting these letter?
I ask because I want to know how time consuming it is. Should I limit the # of school I apply because it might be too much work for the prof?
My experience is that once the letter is written, it takes about 5-10 minutes to submit it to each institution. Usually there is a short form that has to be filled out with basic information (name, contact information, etc) and sometimes also a list of questions asking the professor to rate the candidate in a variety of ways.
So you probably don't want to apply to a huge number of schools (for many reasons besides just that). It's hard to be precise, but I feel like less than 10 is no problem, and 20 is probably too many.
Only your professor can tell you that. Have you talked to your prof?
In my own case, my undergraduates often use the university dossier service or Interfolio, so I only write one or two generic letters (one for academia, one for industry, for example). I do suggest that if there is a job or position that is absolutely critical for them, that I'll write a personalized one. Or if it's a job/department where I know someone, I'll also offer to write personally.
However, that being said, what usually happens with American grad admissions is that you (the candidate) enter the names and e-mail addresses of your referees into the application system. It automatically generates a request to us (by e-mail) to fill in a quick summary (ranking) of the student and then upload a letter. In these cases, I usually do a quick customization.
In any case, the best judge of what to do is the professor. Show them a list of the schools you want to apply to and ask for their advice. You can suggest that you're willing to use a dossier service to take the burden off of them.
For my grad students, I almost always write personalized letters as there is a higher expectation there. Given the tanking of the job market, and some students applying to 60+ schools, this can become burdensome.
I assume that you've done all the other things to make things easier for them: i.e., create a spreadsheet with each department's name, discipline, mailing address, e-mail address, deadline date, and misc. notes, so that the prof can semi-automate the customization process. It's important for you to note which department you're applying to as the automated letter-request doesn't always note that, and it makes it difficult for me to know how to customize the letter, so I use a generic one.
The fun undergraduates are the ones who apply to security clearance level positions. Then I get to have a nice interview with the FBI or Secret Service about the student and their ethical/moral behavior. The feds always super polite and interesting people to talk to.
Its likely that you'll run out of time and/or money applying to schools before your advisor will run out of patience submitting his recommendation letter.
Most U.S. Universities will charge a processing fee around $100 per application. You've also got to factor in time. Unlike undergrad, each grad program will want a statement of purpose/research which shows you've researched the university, and are in the know about faculty and research facilities available to grad students.
Each grad school application should take at least a few hours on your part (maybe more), so I would choose between 5 and 10 schools and make a great application for them. Make sure each application is tailored to the university.
Choose at least one "dream school" that you'd love to attend, and then choose the other schools based on acceptance criteria they post online. The profs you've chosen to write your letters of reference have likely already put several extra hours into your education because they see your potential. They will be fine spending 10 minutes per school submitting.
