At low levels (25-55), caches are numerous, and readily available. There is low risk to being attacked or wiped out by someone. So much so, you usually don't need to send stalkers to prevent others from reconning you.
At medium level (56-65), free/available caches are fewer, and and as long you have decent troops and lots of stalkers to prevent someone from reconning, you can mine it fairly well. You will get the occasional coiner blow you away, but they are rare.
At high level (66+), unless you're a coiner, it's not worth the risk to mine the caches. The return on risk - resources versus loss of your troops - is pretty awful. If you need resources, it's faster and safer just to pillage for resources at dead bases, or raiding other bases. One good raid can retrieve 50K in resources. And at least if you have to raid a base with troops, a good recon allows you to know exactly how much troop loss you face.
With a Level 10 Cache Operations tech, you can only mine 2000 resources per hour. At level 66+, even if you stack your cache with troops, some coiner will just roll in with their multi million offense and toast you. Even if you max out your skill, you can still only mine your cache at 4000/hour, or 12 hours to mine 48K in resources. I can easily raid/pillage 500K-1M in resources in 4-8 hours, with minimal loss of troops. And if you manage to take a cache at high level, it's usually against a high level alliance coiner, who will just toast you and take away any resources you may have managed to mine.
As for the Daily Super Quests, they're fine to play at low or medium level. But again, the Risk vs. ROI is just not there when you're high level.
Level 1-55 - play those caches
Level 56-65 - play those caches carefully, but be prepared to lose occasionally
Level 65+ - don't bother. not worth the risk for lousy rewards.