No it's not wasteful. The fact that a Grunt would trust an Elite even when the odds are 1/1,000 proves that Elites are well trained warriors that can outsmart the enemy. Let's look at the Predators and Elites to see who has the edge
Elites= Trained for War
Predators= Trained to Hunt
Elites= Shields
Predators= A staff
Elites= Powerful weapons
Predators= Powerful weapons
Elites= Travel in groups and wait to attack an enemy with a good plan
Predators= Travel alone and wait to attack an enemy with a good plan
Elites= Can kill the best squadron of marines alone
Predators= Can snap a human in 2
Elites= Camo
Predators= Camo
Elites= Able to sniff out the enemy
Predators= Heat Vision
Elites= Some have Jet Packs to fly
Predators= Only a few Soldiers
Elites= One lifted up the Master Cheif with 1 hand
Predators= Strong
Elites= A Special Elite force was sent to deal with the Flood in Halo showing that they're better trained Elites
Predators= Different types or ranks
Elites= Also have ranks
Predators= Worked with a Human to destroy the Aliens
Elites= Had no choice but to work with the Humans since he had a huge beam cannon pointed at them and learned that his beliefs are false and had to stop the Brutes no matter what
Predators= All but 1 got killed off by the Aliens
Elites= Manage to fight the Humans, the Flood, and the Brutes and still have Elites to spare