Switching out my summoner spells can be a real headache, so much so that I’ve started to go Ghost on D and Ignite on F for every toon and every match. For a long time those two were almost always my go to choices. Then sometime after the big Season 3 patch or right before, I started to select Clarity on F for my mana toons because it just seemed I was burning it a lot faster. A Sona without a heal, for example, is pretty useless if playing bot support in Classic. But I would hit F thinking it was Ignite and waste my Clarity or vice versa, hit F thinking it was Clarity and wasting my Ignite.
So no more Clarity on F. For my mana-dependent toons I just build differently or recall more often. Nothing worse than wasting a summoner spell.