When buying a pen from an expert, they will often ask to see you writing before offering advice as to a suitable nib choice. Many customers assume that they are looking at the actual writing and because of that assumption we are often sent writing samples, these are useless as they do not tell much about the grip used. This is how you can tell whether an oblique nib will assist you.
Should an oblique be used in all cases shown above, the answer has to be no. Many people change their grip rather than making the pen adapt to their existing grip.
Italix brand pens have a thirty day nib exchange, so all is not lost if your initial choice proves incorrect.