If there's one important lesson I've learned in photography, it is to discard as little as possible, and periodically to review my backfiles to see what I missed first time round. Almost always, overlooked gems are sitting quietly waiting to be discovered, overwhelmed at first sight by their gaudier neighbours, but patiently secure in their own merit.
The ease and difficulty of retention and review have changed radically in recent years: paradoxically, what was easy and what was difficult in the days of film have reversed in the days of digital. Roll-film negatives cannot be discarded selectively, and they're a relatively stable, easy-to-store medium (transparencies are a different matter, but I hated the things and rarely used them). But they are tedious to review. The ranks of miniature frames on even a good contact sheet can only hint at what a full-sized, well-printed version of each might eventually look like. It takes patience, good eyesight, experience, and imagination to get the most out of a contact sheet.
For the digital photographer, the situation is quite different. The temptation to delete unsatisfactory shots in camera or after they have been uploaded is very strong. Each frame represents many megabytes of disk space, and when disk space is running low ruthlessness seems the obvious course. On top of that, digital storage is volatile: you need to back up your images in several places RIGHT NOW before your hard disk fails. But even these backups are volatile -- CDs and DVDs use dyes to record data, and dyes fade. Sometimes, it feels like it's all "writ in water". But reviewing has never been easier: utilities like BreezeBrowser enable you to brood over your images like a stamp collector.
For example, it's taken me five months to notice this image, a no-brainer for the "Campus Windows" project. Shame I didn't spot it in time to get it into my Photography.Book.Now book, but never mind, that thing will be twice the size by the time I've finished a full year's worth of window hunting, assuming of course I manage to resist the temptation to go round for yet another year (or two). Of course, another year's worth would simply postpone, prolong, and intensify the agony of editing yet another enormous sequence down into something digestible...
The corollary of this, I've learned, is that it's important not to rush to judgement. For example, I'm quite excited by these three recent images, taken within minutes of each other at a recent graduation ceremony. They are so similar to each other that really only one can survive into any final cut of a "Campus Windows" sequence. But which?