Why would there be diminished gains from the test? Diet is what limits the vast majority of guys as they don't adjust calories as the cycle progresses. There's a bunch of debate on how myostatin plays into this, but you would have to be seriously pushing your body's limits with regards to mass vs time in most of the stuff I've read.
Orals make sense to add/drop during a cycle due to health concerns, or possibly trying to shift gears on a very long cycle - going from a bulk to a cut at the end - but I find doing it that way is lackluster and pretty hard on the body.
I at least can't think of a good reason to do that other than maybe frontloading with short esters, but I'm one of those K.I.S.S. guys.
exactly this.. I'll just add to what's been highlighted..
you can add in compounds (switch) on a long term goal specific cycle.. compounds can be 'synergistic' and one compound can bring out the best in another compound. add to that front loading short esters with long esters and you can get more out of the compound on a 'time' basis (i.e. faster kick in and faster results).
example..
Dbol - weeks 1-4
front load - (short ester test) Test prop - weeks 1-5
(long ester test) test e - weeks 1-22
front load - (short ester nandro) NPP - weeks 1-8
(long ester nandro) Deca - weeks 1-14
Masteron - weeks 10-22
Tbol - weeks 18-22
kick start that with Dbol for 4 weeks and your bulking.. add in proviron at 50+mg a day and and you've freed up more testosterone, helped estrogen control slightly.
then at week 10, add in Masteron or Primo,, you've dropped the Dbol, the NPP and the test Prop,, Deca is still in the system til week 14+,,but your transitioning to a bit of a 'cut' phase but you want to maintain and keep gains.. so you stay on test and add in the non-aromatizing compounds like mast or primo,, run that with a test base from weeks 10-22,,
also, at the tail end you can add in an oral like Tbol, weeks 18-22, , again this similar to Dbol, but it does not aromatize, and your cutting at this stage and maintaining the mass you built so Tbol along with Mast and a low dose of test will keep estrogen sides and bloat very very low while cutting and still stay anabolic enough to get and keep gains.
thats an example of 'switching' compounds.. or using different compounds at different stages of a cycle/stack for specific reasons