Well i think this easy kinds of tapping are pretty useless, beacause you can always play the tapped note on a higher string as well.
For example instead of playing:

-12(t)-8-5-0-

you can as well play

-7-------
---8-5-0-

Of course this doesnt work if you play
-12(t)-8-5-0- on the high e-String.

But usually you don´t need these tappings. I really think that nobody will hear a difference when you play the normal picking technic.
I don´t even think that you are faster when you tap this lick !

But tappings can be really cool though when you play triplets.
The best example is the solo from Metallica - One at 5:44
I think everybody knows it:

-20t15p12-20t15p12-20t15p12-20t15p12-
and so on...

Tappings can also be very cool when you mix them with some hammer-on and pull-off effects.

Mr. Blackfire is playing a very cool lick on the guitar solo (no other instruments) on the Sodom - Mortal way of live Cd

It goes like this:

----------------------------------------------------------
----------------------------------------------------------
-11t5h7p5-11t5h7p5-9t5h7p5-9t5h7p5-11t5h7p5-11t5h7p5-
----------------------------------------------------------
----------------------------------------------------------
----------------------------------------------------------

----------------------------------------------------------
----------------------------------------------------------
-12t5h7p5-12t5h7p5--------------------------------------
----------------------------------------------------------
----------------------------------------------------------
----------------------------------------------------------

This is a very cool one because it´s not very hard and even played slowly it sounds good!

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