Before reading what I am about to say, please note I may range from slightly below average to slightly above average as a player. I say this because
Consistency is an ongoing process that gives you the confidence that perhaps 99 of every 100 games I will be able to set up efficiently and be able to undergo my deck strategy without struggle.
sounds incredibly optimistic. I think it is more like 7 out of 10 to 9 out of 10 depending upon the deck. Unless you are playing solitaire and just give yourself a turn limit. There are too many decks that disrupt setup via lock or simply an amazingly aggressive open, in addition to deck hiccups and misplays.
In general, what is the general strategy one should adopt when choosing what to discard, shuffle in, bring to the top of the deck, etc. How does one prioritize these things? I could use a few pointers here. (Bear in mind I don't have a set deck anymore.)
When it comes to discarding here are a few factors that I consider:
1) How likely will I need it for
this game?
2) How difficult will it be to reclaim from the discard pile?
3) Miscellaneous
As a quick hypothetical example, say you are running Night March and you have
Juniper and a N in my hand, with two DCE and a tech card
at the start of your turn. If you have at least one Night Marcher without any Energy you can use one DCE. Then consider how badly you'll need the TecH card and the other DCE. Got four Puzzle of Times left in your deck? Will shuffling your opponent's hand more than likely help said opponent? Go for the Professor Sycamore. If those are your last two DCE and you have no way of getting them back from the discard? Especially if you also have no other Energy left in your deck at all, do
not use Professor Sycamore. Either N or if that is also a bad deal, hold off for your next draw. Things will be confusing on borderline cases, like where you've just got to take one more KO to win and odds are good you'll draw what you need off of the Professor Sycamore but if you whiff, you'll risk losing the game because your opponent will take out your current Active Pokémon, which is the only one with any Energy on it and those two DCE are your last ones not in the Prized or in the discard pile.