Does DIY Mastering work?

Topic sparked from the increase of DIY Mastering discussions.

So I previewed my mix with the mastering plug I intend to use to master my my ADL 600 song, and liked the sound. I noted values, removed the plugs, exported the wav file into my mastering window, and ummm... started to master. Yet the values would not work.

What are the two most important pieces of gear to a mastering engineer, as pertaining to final quality of sound as opposed to say workflow?

Is reverb ever added at the mastering stage? If so, is it a common thing? If it is something that is done, is there any compelling reason to leave the mix dry until mastering?

Mastering has become synonymous with quality and perfection. The process involves fine-tuning the tracks to make it sound interesting. The tweaked song sounds good on any medium and not just on which it was created. The mastering process renders polish to the whole song. This is all the more important when there are more than one song in the album.

OK. I'm looking for opinions and advice on this subject I've noticed several times in the past.

A buddy of mine is amongst other music things, an expert music mastering Engineer. He has some very big clients to his name from the late 90s early 2000s.

Hey everyone,
I searched for a direct comparison between T-Racks and Ozone. The closest i came to it was remy's post saying she's used T-Racks since version 1 w/ bugs.

I have some very old classic vinyl recording recording at a famous Jamaican studio called Studio One. They already mastered but a very long time ago and lack luster and punch.

I would like to use the Waves C4 to put some punch into the recordings as they seem very light especially the bass.

Is it best to use the upward compressor or the upward expander or simple EQ the mix

Hi I was wondering if anyone knows or took any classes at college that have had to do with a recording studio (DAW's / MPC / Keyboard / mixer etc.) and what they are called. Or any schools online that teach you. Also what degree that would be ..Audio Production..? Recording Arts?
Thanks.

Hope everyone has a safe and thankful holiday.