My personal dredge list, traditional dredge, has 11 creatures, 2 return targets, with 4 bridge from below. 4 narc, 4 ghast, and 3 ichorid are the creatures, and the targets usually vary on what I think is most damaging to the meta. The bloodghasts are realitvely easy to return to play if you play dakmor salvage, which can be gotten if you aggressively dredge through your library, or petrified field which is also a double land drop as long as there is another land in the graveyard (if you have another petrified field in yard you can loop them).
I tested prized amalgam a while ago (pre ballista) and I found that when trying to dread return, it was always a little awkward with timing but the card is strong as a tempo card and is a viable substitute for ichorid if the pilot wants to play force of will. The 3/3 body is very, VERY attractive in a world where walking ballista can kill every creature in traditional dredge with only activation. My personal assessment of prized amalgam was that if dredge was ever big enough where I needed to beat an opposing elesh norn by dread return, but leyline of the void was not big enough to see substantial play, then the card would be a substitute for ichorid.
I saw a list once that played no cabal therapy, no dread return, but tons of 1 and 2 cmc hate bear creatures like kataki, dryad militant, and Thalia v1.0 combined with the reusable nature of bloodghast to try and tempo out its opponent. While certainly different from the normal strategy, I saw it to be very inconsistent in achieving its goal.
There was a list about a year ago that was playing no dread returns or targets, and 4 amalgam in place. I believe Ryan Glackin, the winner of this nyse, place in the Top4 of the last nyse with a list that did this but I may be mistaken. Dread return is one of those cards that can be really really strong, but also entirely unnecessary in some match ups. There is an argument (although I disagree with it) for cutting dread return in general because the main deck you need to beat with it (oath) is basically extinct. I believe dread return is still necessary for dredge but that's a separate discussion. Against shops dread returning a creature can be the difference between a win and a loss if you can fire it off. At the same time the card could never resolve and you can win or lose all the same. One card I've seen that some people are getting hyped about is hollow one, which costs 2 less for each card you cycled or discarded during the turn. This card has some serious strengths, and weaknesses, depending on how you view it.
The bottom line for creature packages is this, it all depends on the type of list you want to play. Traditional lists don't allow for a lot of variations because of how tight the space. More experimental lists that appear usually online, are different in that they often play a different strategy from traditional dredge so they are not as constrained to run the same number, or type of creatures that traditional dredge runs. Hopefully this helps a little!