This is totally dependent on the guy.
There are guys who can go out two nights a week, but they hustle their asses off, they are hungry, they're extremely perceptive and strategic about what they're trying out and learning, and they progress very, very fast.
There are also guys who game daily, who almost never change things up, and have very low EQs or otherwise are not intuitive learners, and despite hundreds of outings and thousands of approaches in a year they aren't much better than where they started out at.
In general, if you have a normal ability to learn and improve, and you are going out and making it worth it, though, going out often enough is key for a few reasons:
It is going to compel you to really prioritize going out, and make it a key thing you focus on, and your obsession for the moment. That way you are directing more of your mental energy into figuring out women and excelling more in the game
It is going to give you more touch points with women, more chances to score some Ws that will help with your motivation, and more opportunities to take things deeper into the interaction so you aren't just practicing basics all the time
When you stack up several outings in succession, it creates momentum, which is fairly important for learning. Imagine trying to learn how to play piano taking class once a week + never practicing at home, versus having class five days a week + practicing at home each day, for instance.
What do you learn each time you're out? You need to come up with your own learning plan. Or complete the assignments from the diagnostic quiz or one of the products like One Date or my book.
For keeping expenses down... see my article on broke-guy game. Skip to section #6. I know you've read it before; I think I wrote it for you.
A few ideas on the stuff I didn't cover:
Can you car pool? Easy way to save on gas
Is there nowhere cheaper you can park? Look for street parking, even if you have to walk a little farther
Get on the lists for places with covers. If the don't have lists, meet the promoters and have them get you in free. If they don't have lists or promoters, go on the off nights, befriend all the bar staff, and in a month or two of going 1-2 times per week on slow nights you should be able to go on busy nights and get waved in. Or just go places that don't have covers. Often the best places for picking up only have a $5 cover or no cover. The really expensive places tend to be horrible for picking up at
Also, anything wrong with day game?
Re: more men leaving the dating game, well, more women are too. But not as many as the men are.
The problem most guys seem to be having is the decline of the nightlife scene. There was a similar phenomenon in the late 1970s when the discos were dying and no one was going to them anymore. Then Saturday Night Fever came out and everyone was back in the discos again. Then at some point they died back off, later to be replaced by modern nightclubs. But there was a gap in between, when people really weren't going out much, and there was much less of a nightlife scene.
This is a normal thing that happens, and there's a cyclical pattern to it.
Nightlife dies, then after a while it resurrects. Then it dies off again, then resurrects again. Typically in slightly different forms (I don't think too many people today would want to go to a 1970s disco. Just like more and more people today don't want to go to a 2000s nightclub. Sooner or later some other kind of nightlife venue is going to come along that people DO love going to, and it'll come surging back... for a cycle, anyway...).
Regardless though, day game and social circle is as good as ever.
Most of the complaints you're hearing are coming from pure night gamer guys.
Also Tinder guys, lamenting the decline of the dating apps (which are totally saturated with men, and which the best women aren't on).