In fact, the difficult part of subtitling is how the text will survive the constraints of time and screen space. Any translation should be fit for only two lines that will be shown at the bottom of the screen. If a line would be six or seven words, then you are allowed to use 15 words. When such limit is exceeded, editing should be made. Many factors should be balanced in order to get a good subtitle. If you are given a word for word translation as subtitling for your video, you may not have a problem of space on the screen. That would be Ok. But as you know, we speak with a faster speed than we read.