In film editing, one marks the workprint with grease pencil where an optical is desired, but the actual appearance of the effect can only be imagined. Non-linear systems will create a viewable effect more or less instantly. Non-linear systems also have a number of disadvantages. The second disadvantage is resolution. At these resolutions, fine detail is lost and the image appears somewhat pixillated.
Higher resolutions consume more disk storage, which adds extra expense.
In film-based editing, of course, one can drag one's cut reels down to the screening room any old time and have a look. In non-linear, even if a production has the budget to print dailies as well as telecining them, assistant editors must output cut lists from the Avid and manually conform the workprint to the editor's work on the Avid. A fourth disadvantage is the inevitability of downtime. Avids, on the other hand, experience a variety of technical problems ranging from software conflicts to hardware incompatibilities to corrupted files to defective cards. Any one of these can stop editing dead in its tracks, and fixing it can in some cases take days.