Time machine - timing question (how often) and applications question

Question

1. A hypothetical: if I boot up the iMac and make changes to a file and shutdown, all within a 15 minute time frame - - then, for whatever reason repeat that later the same day because I need to change the file once again (and again, just another 15 minute session) - - - has Time Machine captured both or either of those changed files?
What if these two changes were both made within the same hour? Which backup if any would it capture?
I'm letting the hourly backup timing confuse me. Does Time Machine capture changed files at startup, as long as at least 1 hour has passed since last backup?
2. Applications - is my assumption correct that you don't want to restore Apps from Time Machine since you're not likely to restore plist or other related files that reside elsewhere on the hard drive?
Thanks in advance

Answer 1

DHodges wrote:
1. A hypothetical: if I boot up the iMac and make changes to a file and shutdown, all within a 15 minute time frame - - then, for whatever reason repeat that later the same day because I need to change the file once again (and again, just another 15 minute session) - - - has Time Machine captured both or either of those changed files?
Probably. When your Mac starts, it will run a backup immediately unless a backup was done within the previous hour. So assuming the last thing you do before powering-down is to save the file; if "later that same day" is under 45 minutes, the first one might not be saved; if it's over 45, depending on exactly when you save the second version, either the first or second would be saved on that backup.
I realize this is theoretical, but Apple recommends sleeping your Mac instead of powering-down unless your iMac won't be used for "several days." See: [Sleeping your Mac vs. Powering it Down|http://web.me.com/pondini/AppleTips/Sleep.html].
I'm letting the hourly backup timing confuse me. Does Time Machine capture changed files at startup, as long as at least 1 hour has passed since last backup?
Yes.
2. Applications - is my assumption correct that you don't want to restore Apps from Time Machine since you're not likely to restore plist or other related files that reside elsewhere on the hard drive?
As Thomas says, that's usually not a good idea for complex apps (generally, the ones that come with their own Installers), but is fine for those installed by drag & drop.
And yes, even for those, you'd have to restore the preferences file or re-enter the settings, and of course the data, too, wherever that is.