If you're not seeing 6-8 encounters per day/LR - talk to your DM. See if that is something the players and DM want to try out.
That's not the problem. The problem is actually pretty deep. Short rests were supposed to fix the five minute adventuring day, but they haven't done that at all, and the 6-8 encounter recommendation carries it's own problems.
1. Encounter require time to play, especially if you use a battle grid. 6-8 encounters means setting up 6-8 encounters. If you're only able to play 3-5 hours a week, it's actually somewhat reasonable that you don't have time to fit in 6-8 encounters unless you're literally running 6-8 connected rooms. Yes, even if they're at half difficulty like 5e encounters are. Sure, you could use two game sessions to split one adventuring day, but my experience is that few game groups do that. Most game groups want to start a session at the end of a long rest so that they don't have to remember their character state from a week or two ago at the start of the next session.
2. Because 5e encounter difficulty is heavily lowballed, 6-8 encounters can be extremely easy, not challenging, or not interesting. In some groups, the players can feel like combat is a waste of time in a game primarily about running encounters. This means the group will just run fewer, more challenging encounters, but this has it's own problems because it eliminates one of the ways 5e tries to encourage you to short rest.
3. There is no reason to short rest. Or, rather, there is no reward for
not long resting and playing through more encounters in a day. Since the game still has attrition elements like long rests not recovering all hit dice, the cost of a short rest is often not a lot lower than the cost of a long rest. Since a long rest does everything a short rest does and more, the only reason you ever really need to short rest is when you're under time pressure, which simply isn't appropriate for
every adventuring day in every campaign. Worse, if your campaign has real time pressure, then you often run into situations where the players can't
short rest, either!