It is a good general rule (probably in life, but certainly in litigation) to make your best points and then stop. It will be very rare indeed that there are more than half a dozen or so really good points in any case. Good points get rarer on appeal: if you find yourself drafting a notice of appeal that runs to more than 4 or 5 separate grounds, the chances are that your appeal is a weak one.
There are exceptions of course. Occasionally there is an employment tribunal decision so bad that there is an almost infinite number of ways of describing what’s wrong with it. If you’re faced with one of those, your task is quite hard: drafting grounds of appeal will feel a bit like performing an autopsy on a frog that’s been through a liquidiser. It’s clearly not a functioning frog any more – it’s frog puree – but how to put a finger on what precisely is wrong with it? But even in that kind of case, you will do better to make your 3 or 4 best points – you only need to win the case once, after all.