Simon 10, you are dead right about what to do when hours building. Do we just stooge around straight and level and fly to the next airfield for the $100 sandwich?
That way you learn nothing, and you get no consolidation training. I asked the same question here about 150 hours ago and got some good replies, but not as many suggestions as you might think.
After I got my PPL I went to different schools and asked for further training. Some was excellent, most very good and some a bit iffey. Most started to teach the syllabus of the CPL or extensions to the CPL that exist in certain countries. (mountain, low level, heli lanes, low level nav etc.)
Left on my own, I try to keep to a discipline of exercises, such as in one hour of hours building I will do several circuits, aiming for perfection. (Never got there yet). Then a few slope landings, then a few turns around a point. A couple of pinnacles, a couple of auto's (if the owner/country authority allows this solo) then return to base on a fixed speed, heading and altitude, plus or minus nothing.
I remember a famous musician at the top of his profession being asked how he practiced. He said he did scales. Same with us, if we get the basics near perfect, the rest falls into place.