These benches are fine, they are fine as built, the owners are thrilled but as a general fabricator with substantial experience and having built a dozen or more on various jobs and 200 for one alone it isnt the way it would be done.
I tack leg table end assembly up first, all square (in production we had plate jig, lay plate on backmark where legs went tack a set on, need to square/plumb only one direction once. Lay the long stiffners in, stitch weld along it a zip each side every foot, I think we put 3 welds along 4 ft bench, stood up second set of legs, tack and install 2 more angles for a shelf up about 18 inches.
While all this frame welding doesnt really hurt its a waste, there is almost no stress on welding over a post or at a connection in this type of bench, any deflection occurs mid span.
I was looking for a picture of the production one, couldnt find it right now but in general is similar to this scrap but based on the connections above with sq tube. About 8 inches of light weld made all he connections at a corner and another 6 or 8 spread along each cross member. Left it all so a board or expamded metal sheet could be tossed under for shelf. Gread ballast and wasted space that can be used to toss stuff underneath.
No holes in the top and a vise receiver is not a bad idea especially since in small shops this tabel is not only a welding table its a work bench, its really a work bench that doubles as welding area.
I will find pic. The only finish work we did was with 7 inch sander to smooth sharp edges from shear and zing the corners. No weld grinding or hand cutting at all and even sanded before we put it together.
That was for a remna factory, I went to steel yard as needed, couple times a week, buy4 1/4 X 8 plates and had designed a simple modular scheme, whack it up on shear according to demands in common sizes with a few spares, buy 10 pcs of angle, gang cut it right there on big band saw, same for tube legs, 10 at a time, lay it all on the plates basically and even had my helper weld most of it up. Took him about 15 minutes. Actually assembly was about 30, there were other overhead concerns, as I recall I billed about 1.5, back then it seems it was about 85$ for assembly delivered. Been 20 yrs.
Took a couple pallets to the steel yard, loaded all pieces on them. My only point here is that not all the stresses occur where they seem at first glance, the welding is primarily a little glue to keep the pieces from sliding around.