security issues aside, how often are reservations, "secured" or otherwise, actually held?

if the restaurant is not very busy, then a reservation wasn't necessary in the first place. and if it's busy, i usually find myself waiting 5-15 minutes anyway while they "get the table ready." regardless of which, there never is really any risk to the restaurant of no-shows, because "my" table will get seated whether i show up or not.

of course, opentable points are a separate consideration.