I keep hearing about players not being able to complete 800 point games in 2.5 hours. Is this really the case.?

I have played quite a few games and not gone over 2.5 hours.

What are other peoples experiences? If your games are taking longer, are their specific reason why they are taking so long?

In my experience, most gamers who complain games take to long are also the ones who love to tell stories while they play, slowing down the game.

When I play a game at my FLGS we take our time with reading up on rules (especially after a new RR or unit is released) and we tend to play 3 hours or more.

I only played at one tournament so far but we stayed in the time limit of two hours. Mostly because I got slaughtered XD

In my experience there are two types of Legion Games: One where one side hase a huge advantage (either by list, play experience or sometimes just luck with the dice) where the game is decided after 3 rounds and one side gives up. This also happenes when one or both sides act recklessly and figures are taken from the board with shovels. The other is where two equally skilled players with equally potent lists face each other and every activaction counts and could turn the tide. Both players play defensively and think twice about every move and very few models actually die because there is so much positioning, hiding, and dodging. These games often last 4+ hours but are the most fun and intense games (and don't feel like they are dragging forever). Most Tournament games are of the latter kind.

Also the meta for Legion is more activations is best. This takes more time. X-Wing back in the day had about an hour each match. This is a very different game when you have two ships per side compared to 8 ships per side.

We routinely finish six round games with 10-11 activations per side in two hours. The key is knowing your list and the game and minimal frakking around. Takes focus.

For most casual games there’s no rush.

Doing some rough Math,

1-2 hour game time. 6 rounds til forced end if no other winning conditions apply. Equals 10-20 minutes per round, 5-10 minutes per player each round.

If each player for example sake started with 10 units, each unit upon activation would have 30 seconds-1 minute to complete its actions. Time increases as units are defeated progressing through the 6 rounds.

It is very plausible to finish within 1-2 hours or less. When it comes down to it... add time for; more units total, intentional slow play, inexperienced players, debating or scrutinize rules/keywords, strategic & tactical thinking, etc etc. While shorten time for; less units total, experienced players with quick decision making, very knowledgeable with rules, heavy unit loss, conditions met quickly, forfeit, etc etc.

If both players make decisive moves with each of their units while knowing the rules, you should be fine. Otherwise, expect the game to take a bit longer than it has to. I'd also add, aim to be upfront and honest with your opponent with your game expectations, so you both know where the others mind set is. If you are serious & competitive say so, if you want a lengthy story telling casual game say so, on a strict time limit say so, don't care how long it takes say so... Either way there is no right or wrong, however competitive games lean more towards expecting game to be over in 1-2 hours if not less, while a casual game will be the same or maybe not. There is a difference, and communication might help with that so you both are aware rather than be upset and blindsided.

At the last tournament I attended, most of the games were completed in the time limit, with a few going over into the overflow time, and some by the less experienced players not completing in the time limit.

As above, there are many factors that can change the playtime of a game. A few of the players at my local store have qualified for the High Command Invitational at Adepticon, and they have been practicing with a strictly enforced time limit. Despite being experienced players, they do on occasion run right up to the 2 hour time limit. I have definitely noticed that games between two high activation lists tend to take longer than those involving medium or low activation lists.