Work hard, not smart. That's what they always say.
Of course what they mean by that, is what I call the "inefficient engine metaphor". If I have an engine that is running at a measly 4 miles per gallon, sure I can keep adding fuel into it. But what if I could improve the engine to get a more respectable 8 miles to the gallon? Not only would I get that Greta Thunberg protest off my driveway, I would actually get twice as much done with the exact same amount of effort.
If you want to be mathematical about it (who doesn't?), then you can think in terms of efficiencies. If I'm doing 10 hours work per day, but operating with 90% waste (a bit like a government department amirite?). Under that paradigm, I would have to work 20 hours a day just to get 2 hours of output.
But if I can improve efficiency up to say 80% waste, then I can double my output without having to work any more hours. So what sits behind those 4 words, when you unpack it, says a lot more about how to approach your targets. There can be often more to gain from improving a process than throwing more resources at it wastefully.
Except, what if you're talking to someone who is just really, really lazy? What if someone is doing 30 minutes work a day, and getting only 3 minutes of output done (i.e. 90% waste). Well that person can comfortably 20X their output simply by just working a full days work. So they actually have more to gain by working harder not smarter, huh? What's going on here?
Truth has limitations
Truth is not absolute - things are only true up to a point. Let me give you an example. Murder is wrong, right? I would generally agree with you on this one (although I've seen some questionable driving that has made me want to relax this constraint), but I am sure I can cook up a situation that would change your mind.
What if I enter a room, I have a pistol. 20 yards away I see a family tied up, with a shotgun to their heads, and I see the assailant reaching for the trigger. I have about a second to make a decision, not enough time to cross the room and try something else (and risk getting my head blown off as well). Do I shoot?
You could definitely make the argument that shooting the other potential murderer is the correct thing to do in that situation.
I'm confident that you could give me any "truth", and I could cook up some situation where that piece of advice is no longer workable. Every statement has it's domain where it rules, and it also has a wilderness overrun with bandits where it gets its ass kicked.
Context and trade-offs
Rather than pithy one-liners, I prefer to distill wisdom into trade-offs. Oftentimes you are trading two things against each other. The work hard not smart, is really speaking to a trade-off between where is best to spend your time. Is it best to add effort into an existing process, or is it better to allocate your effort into improving the process?
A lot depends on the maths I outlined above, i.e. how good is the process, and what are your current resourcing levels? You can make a call about the trade-off once you have that context.
The best solution might be a bit of both. Maybe you need to work a bit harder, and a bit smarter. It all depends on the situation.
You are looking for the highest yielding areas. The question you need to ask yourself is, what is going to get me the most benefit? Where can I invest this time for the highest yield?
Honestly some people are not even following a process, so how am I going to tell them to work smarter? They haven't even started working yet. That person would be best served by grabbing any old process and implementing that, then coming back around a month later to analyse it.
How about this one, "a bird in the hand is better than two in the bush". Ok, but always? I mean, I get what they are saying. They are saying that certainty has value. That it can be better to guarantee a smaller outcome than risk a larger one. But that all depends on the percentages involved. Again there is some simple maths here, known as "expected value", but I can again make it easy.
If you have a game where you can pay a dollar to play it, and the way you play is you flip a coin. If it's heads, you win, tails you lose. Is the dollar in your hand better than the dollar you could win playing the game? That depends if it's a fair coin or not, and how much the prize money is. If the coin is weighted 90% to land on heads, and the prize is a hundred dollars, then you play that game every single time.
In that situation, the bird (i.e. dollar) in your hand, is mathematically worse in every way than the available "birds" in the bush.
So again, that is a phrase that is speaking to weighted probabilities and expected value. Of course, often in life, the coin is the other way around and the payout is much lower, in which case of course you are better holding onto your dollar.
Learn when to switch
So with many things, learning when to apply one idea, what the cut-off point where that idea ceases to be useful and another idea rises to prominence, is the real art of living.
Just having social media posts where they highlight the flaws of one idea and the merits of another one, is only true in the context they are presenting it.
You can equally find another situation where the value of those ideas are inverted, and the "silly" one suddenly becomes the smart play.
This takes time and experience to develop this knowledge. But you have a much bigger head-start if you realise that you are looking for two opposing ideas to compare in each situation, not a single rule of thumb you can apply everywhere.