I don't know that it's as simple as just changing it to simple mode. I run on average about 200 db's, all fully logged. On any given day maybe 25% are really being used. I run log backups 4 times a day, but I run a second job that backs up any log over 50mb (arbitrary, pick a # you like) and then shrinks the log. This gives me a usage based backup, plus keeps disk usage in check. The time it takes to shrink a log is pretty small compared with a db backup. Switching to simple doesn't alleviate the problem of space usage, one big transaction can balloon up the file size way beyond what it "normally" is.
Andy