But ooos - you still only have x number of lessons per week to plan for, just as primary school teacher do. It is the same number of hours work that needs filling with meaningful work - the same number of hours that require short, medium and long term planning.
In secondary when teaching classes you do often have the advantage of duplicate lessons. I taught ICT so would have maybe 3 or 4 Y7s a week for example I didn;t have to produce a whole new plan for each of those 4 classes - I simply had the same long and medium plans, but adjusted the short term plans.
The assessment is different but not necesarily less time consuming, especially when levelling literacy work for example. Some aspects of secondary assessment does take longer and there is often more of it.
Primary school reports are longer than what you would expect from a subject teacher in secondary. In primary the teacher would have to write reports for several subjects per hild. In secondary you write one report for each child. I reckon it probably evens up.
You probably do have more parents evenings in secondary,a lthough IMO primary teachers seem to see parents a bt more often and certainly that is the case on a day to day bases with parents popping in more often. etc
There is a lot more resource prep IME in primary, and more time spent on presentation and display type work.
Having seen both sides my personal opinion is that the two jobs are actually very different jobs. Neither is IMO harder or tougher than the other.