Let's be real, im impatient to get out there and can't afford the advanced scanner just yet. Do I really need it or it is more of a matter of convenience?
ok the basic disco will only find things out to a short distance. it will miss a lot unless you fly 500 ls away from the star both sides of the system, and rescan. that takes time. the inter will scan only out to 1500. it will find a lot more but i have seen gas giants orbitting a binary system at 3000 ls out plus. you wont see those, or distant stars except with naked eye - and not any planets they may have around them.
the ADS finds them all. you can then pick close targets to detail scan. it depends why you are going out there - but not so much as you think. because if you are going out purely to earn money, you need to prepare, to maximise profit and you really need ADS and the DSS to max the money. you will also need to engineer the FSD for max range - you wont be using it when you find undiscovered systems, but it gets you past the 2 to 3 thou ly sphere around the bubble thats been explored to death, and gets you back again quicker.
if you are going sightseeing, you will likely be willing to spend more time out there, more time flying around. but an ADS is still essential imo because even with flying around, and scanning with an IDS you still might not spot a distant star and to earn money from any planets around it or see if there is something strange (or even to scan for them) might require flying 100,000 or up to 500000 ls to the system to get in range. ADS is one honk and that money is made even if you dont want to fly out there (of course if there is an ELW or a black hole there its probably something you might want to fly out and see).
so it comes down to, you might miss something valuable/interesting without one. idk why you want to go out, making it harder to advise. you CAN get by without a DSS if all you want is to look at things. but it makes using an srv on planets to get mats for FSD injection random chance. for the serious explorer, the ADS AND DSS are a must; along with FSD engineered for range, the biggest fuel scoop you can fit (less time scooping means less tedious wasted time) and an srv and hangar to get mats for FSD injection and repairs/fuel for your srv.