My HDD/SDD erasure scheme:
1) Write randomly-generated data to the disk until it's full (just create a file and write until it runs out of space).
2) Delete the partition.
The likelihood of someone scrounging a disk for data, after the partition has been deleted, is extremely low.
The likelihood of someone expending the massive amount of forensic resources that are needed to try to recover tiny fragments of data (keeping in mind that if any can be recovered by painstakingly analyzing residual charges or whatnot, that there is going to be a stupendous amount of noise in the signal that anything recovered is almost certainly worthless) is virtually zero.
So, yes, people who advocate insanity like 7-pass erasures are high on paranoia. Nobody in their right mind is going to go through that kind of effort to scrape out a few badly-mangled bits unless the data is extremely valuable and the attacker knows that it's extremely valuable. So unless you have data that's worth millions or are trying to keep top-secret foreign government files from the NSA, a simple 1-pass fill with random data (the randomness is to counter any compression or deduplication mechanisms that may be in place) is more than enough.