I try and plan for as much as I can TSR2....I also agree with daz211 that there should be no desperate need to use toilets on short hauls..
Also like daz211 - I have never had occasion to use a loo despite taking my own tissues, supplied tissue is cheap and small.
Silverhawk and TSR2 both have valid points though IMO....
That's what airlines like FR are counting on, and no you can't plan for every eventuality...This is why I will never ever return to Tenerife.