I will virtually NEVER, EVER need to artificially lengthen a tool to get sufficient torque on a nut or bolt. So why not?
I have more than a single wrench. (Sorry, substitute "spanner" for "wrench".) Multiple tools to fit multiple problems. Large, unfriendly nuts and bolts, that take larger amounts of torque to turn are solved using larger tools, able to apply the torque needed. When needed I use a penetrating oil, or a bit of heat carefully applied in the proper place can help too.
Next, I tend to avoid an open end wrench whenever a socket wrench or a closed end wrench will work. A closed end wrench will not slip off the bolt, so there is less of a problem. As well, an open end wrench can tend to round off the nut/bolt one is turning, so it is a poor choice. This is why a 6 sided socket is my preferred choice for most problems. Since you can buy closed end wrenches that ratchet, they are also much faster to use than a simple adjustable wrench. (Avoid those gimmicky open end wrenches that claim to fit ANY size nut or bolt. They never work as well as claimed, and risk rounding off the corners when you work them too hard.)
On the MOST difficult nuts/bolts to turn, I'll pull out a breaker bar. This is a moderately long, strong bar for sockets, and I use a set of sockets designed for an impact wrench. They are properly hardened sockets, designed to take extra torque and abuse.
My point is, have more than one tool to fit the problem at hand, not one small tool and a huge piece of pipe. Expand your set of tools to solve the problems you find. This is well worth the investment. You don't need 100 different tools, just a few carefully chosen ones, a set gradually expanded as they become necessary. Otherwise, expect a lifetime of nuts and bolts with ruined heads and broken tools.
Think of it like this: why buy the same tool many times after breaking it over and over again, instead of buying several tools that will last your lifetime? This brings up one other point, to buy good quality tools. I expect to never need to replace most of the wrenches in my toolbox. So avoid buying a set of cheap tools. Go for quality.