The party I am in is currently involved in an attack against a fortified manor house and knows that there is a subterranean component to the compound as well. We are certain there are a good many fights between us and the cult leader that likely has a lair at the darkest depths of the dungeon.
The party consists of 6 players (Monk, Inquisitor, Occultist, Investigator (me), Barbarian, and Ranger) at level 6. We have a higher than recommended point buy for the module, as well as more players than normally recommended. We're well equipped and using the Automatic Bonus Progression system. My point is that on the front of it, we can survive most "normal" encounters with little help or resource expenditure. However, when things get hairy, encounters can get pretty desperate; we have seen a couple character deaths in the game already.
Before we began our assault, we appropriately used long term buffs, as well as applied a few short term buffs (we did nearly TPK the first time we came here). It turns out the "surface guards" were significantly fewer than were expected, and that when prepared (as in having weapons drawn before we knocked on the door) it was a fairly trivial encounter. Inside the courtyard as well were some potentially dangerous enemies, but we were prepared and made short work of them as well. I should note it was a slightly long fight (really it was two distinct encounters flowing into each other), but the dangerous enemies were dispatched quickly. After that though, it was all quiet, and the short term buffs wore off as we explored.
During this fight though, many of the players expended some fairly limited character resources. The Inquisitor pronounced one of his 2/day Judgements (to fairly limited effect) as well as some of his few rounds of Bane on these enemies, the Occultist used Focus Points to give Bane to someone, a good number of rounds of rage were used, etc. Frankly it was overkill. Besides rage, most of these abilities were activated after the enemies were killed, in preparation of unseen, and ultimately non-existent, foes.
Now part of this is of course part and parcel of playing this sort of game, and I want to say I respect that these players are certainly having fun doing these sorts of things. Still though, we now have a good bit fewer resources available to us as we make our delve into the dungeon, and we're just through the front gate.
The notion of the "15-minute adventuring day" has been thrown around the table before, and it certainly has been downplayed as strategy. Resting is certainly fairly risky here, as the stakes apparently are that the entire town will be destroyed if the cult's ritual is allowed to complete (and we don't know the timetable on that).
I want to say something about the rate at which we're using resources, but I don't want to be that sort of player. I don't want to be telling other people how to play their characters, but at the same time, I don't want it to take a character death or some major failure to hit home the need for pacing the use of resources.
What are ways to broach the subject of character resource usage with the party that won't come across as controlling? Or perhaps is there any perspective I should be taking to minimize my concern over resource usage?