Erase or format CF cards ?

It is better to format the CF card when full or ease all photos ? Is either of the two options the same ? I read some where that one should not keep deleting photos at random on your CF card as it develops bad sectors.
Darryl

Formatting not only deletes the files, but clears out the (now empty) directories they're kept in, so you get a fresh start. It's also faster than erasing individual files.

Modern memory card controllers spread the wear uniformly across all parts of the chip(s); random deletions won't cause bad sectors from overuse (which is, in any case, around the 100,000 record/erase cycle limit)

Thanks Jon,
So I think that formating is better. Another question ... are slower CF cards reliable when shooting fast click click click as they are much cheaper, maybe not for pro use but just test shots
Darryl

The only problem with slower cards is the buffer getting filled and not being able to dump to the card quickly. The recovery time is what becomes the issue as the camera has to write to the card...and in the case of a slow card...it can take a very long time to go from buffer to card.

They're just as reliable; they just will take longer to write from the buffer to the card. And you can fill the buffer single-shot mode if you're shooting a series. Faster cards will give you more buffer room (because they can write more while you're between shots) and get you back shooting sooner after the buffer fills.

Thanks for all the information
Darryl