So you can only train 2 times per week. Or maybe 3. Or maybe as little as once per week (open mat Sunday, is that you?)...
Is it even worth it at this point? Can you become better when you don't train as much as some of your training partners do?

Yes, you can. Though there are some things that you'll need to do, in order to make the most out of your time on the mats.

SET REALISTIC EXPECTATIONS

First of all, don't stress yourself out because you're not training as much as you'd like to. Sure, it would be great if you could be on the mats 6 times per week, but the matter of the fact is - unless you're a professional athlete or coach, there are some other obligations that are much more important.
Such as your career or/and studies and family.

So, set realistic expectations and enjoy your time on the mats.
If you enjoy it and don't stress out about "what should be" too much, you're going to appreciate your journey so much more.

BE FOCUSED

Take a look around you the next time your coach is demonstrating a technique. How many of your training partners are truly focused on what's being shown?
And ask yourself the same question... Do you stay focused? Or do you zone out?

Same thing when it comes to drilling techniques. Are you just going through the motions? Or are you actively thinking about the details, the bodyweight and grips placements, the balance...?

You have to stay focused if you want to improve. Letting your mind wonder elsewhere and just going through the motions is going to be extremely detrimental to your progress.

HAVE A GOAL IN MIND

One of the most common mistakes that BJJ students make is not having a goal when they roll.
They just do whatever comes to mind next.

But this is a terrible approach. You need to set goals. even if it's just from one training session to another.
From the moment you slap and bump, you've got to know what you're aiming for. Be it a specific guard pass, sweep, position, submission - it doesn't really matter.

What matters, though, is that you make a choice. That you pick a technique that you want to focus on and then work on it for the next several training sessions. Weeks, months even.
By adapting this mindset and approach, you'll be much, much closer to fulfilling your potential.

TAKE NOTES

Yes, time is tight and you're probably rushing to get home/to work after class. But taking as little as 5-10 minutes after training to note down the most important details is going to be more than enough to propel you further forward.

You don't have to go into too many details. Instead, write down the things that you've been intrigued by and that are vital for properly performing the demonstrated techniques.
This will improve your technique recall tremendously. Plus, the more you do it, the better and more efficient at it you will become!

WATCH INSTRUCTIONAL VIDEOS

And as a last big piece of advice, if you can, then take some time aside to watch instructional videos.

For example, if you can't make it to training because the schedule is tricky, then take a part of whatever free time you have during the day - and watch instructionals!
Pay attention to the details, the setups, and then try to apply them in your next training session. If they don't succeed, then revisit the instructional video and troubleshoot. Rinse and repeat.

It's extremely important that you don't just watch them and then "leave it be". Watch, apply, troubleshoot, and then reapply the techniques when you roll.
In addition to the previous 4 tips, this one will ensure that you're taking full advantage of every single class.