Even on a focused search... I infrequently have trouble finding a warzone match... if I do, I work my way up to expanded searches (going to balanced first)...
Just a heads-up, the adoption and integration of TrueMatch into Halo 5 (in 2020) has rendered the search preferences of Focused, Balanced, & Expanded as being superficial options to restrict or expand what data centers are available to connect to. They don’t matter anymore because TrueMatch automatically adjusts what data centers are available for a player to connect to based on its understanding of the available and suspected makeup of the population.
I've heard some talk of this, but don't know much about it. I can tell that I absolutely notice a huge different in the ability level of the players I'm matched with depending on search type... so I just throw that out there for what it's worth. I do much better on matches with a focused search, whereas on expanded, I get completely wrecked... my company liked to do expanded searches because of the wait times (their words not mine)... sooo... there may not be much truth to the search types, and maybe I'm crazy... but I feel like I do better, and by an large, my stats bear that out...
Originally the Focused option not only restricted the data center you could connect to to your closest one, or perhaps in some locations it was the closest few, but it also ensured that the search parameters, regarding the player skill gap allowance, could not expand abruptly until after 4 minutes into the search. So for the first 4 minutes of the search the skill parameter allowances would expand progressively over time and couldn’t jump to the max or an unlimited allowance.
Balanced and Expanded only dealt with the number of available data centers. Balanced would limit the data center options to a player’s general region while Expanded theoretically made all, or nearly all, data centers available from a global perspective. Under both of these options the search parameters, regarding player skill, could potentially broaden abruptly instead of being restricted to expand slowly for a period of time. The reason for allowing the abrupt parameter expansion to occur whenever during the search was so that highly skilled players and stacked fireteams that had already exceeded 5 minutes of searching would receive improved chances of finding a match before being timed out.
In other words, the Focused option provided some protections from being pulled into a wildly unbalanced match in the first 4 minutes of the search. And no such protection was provided to the other two search options; however, the trade-offs were that Balanced and Expanded increased the available population at the cost of connection quality which often meant that if you weren’t being sacrificed to an unbalanced match abruptly you’d likely receive more balanced matches on average than you may find searching under Focused which was greatly limiting the available population to match with.
Later on they modified the Focused option to significantly lessen its protection time period and also introduced a similar period of protection to the Balanced option. After that I believe they removed all the protections, but that was shortly prior to the implementation of TrueMatch into the game (in somewhat early-ish 2020) which rendered these search options irrelevant. Any anecdotal experiences like what you mention is now just a coincidence and essentially people reading into it what they may want to believe.
