My in-laws bought a cute but ancient (1940s) house a few years ago, and while the porch looked good from a distance, it was rotted and structurally unsturdy. This year one of the deck boards broke, and it was clear that the whole porch needed to be replaced as soon as possible. So we built them a new one.
Regarding the previous porch:
Only one of the posts was cemented (with very little cement), and the rest of the porch was resting on free-standing cinder blocks and bricks… Some of the posts weren’t buried at all, allowing the railing to give.
Regarding the new porch we built:
Four of the six 4×4 posts are cemented with 100 lbs of concrete each, both footer and anchor, and the whole porch is anchored to the house with thick lags. Support beams are 12″ on center, mounted with angle brackets with 6 screws each. We measured and cut our own stringers. All screws are exterior Deckmate star-drive. All balusters are both brads-nailed and pocket screwed.