What is the largest battle you've played through in 3.5?

[Coidzor]

Some players think it's a bit *******-ish of the DM to roll all archers targeting one unit. It was the session when I figured out even if the party doesn't say it, they kinda want the DM to go easy on them.

Thinking it's in poor taste to focus fire 16+units, about half of the enemy force of 30, on one character isn't exactly wanting the DM to go easy. Nor is it wanting the DM to go easy to dislike encounters which are set up to guarantee failure on the part of the players.

Of course, if you just meant having the actual archers, which were... 4/30 of the entire enemy force all attacking the same character, that's... honestly it's kind of bizarre that they'd pick up on that with how the other enemies would be divided up against the rest of the party anyway.

What was your largest battle you've gone through without resorting to variant rules for large encounters?

Probably about 20-25 units when multiple waves of opponents in the Battle of Brindol from the Red Hand of Doom adventure stacked up with one another to try to break through us after we got cocky and advertised our position. Our party of 7 had a few NPC allies, though we'd sent most of them a ways back to ambush any regular hobgoblins that slipped by us while we were fighting the actual threats.