3 - I think that as it stands right now, I can make one preset for my band's set, with 5-6 scenes total. I can add scenes and presets for new songs as we add them. I want unfuckwithable tone, and the flexibility to get whatever tone I want down the road.
This is how I use my AxeFX. I play mostly original indie / alternative rock and I have one patch that I use for 98% of the songs my band plays. It's basically the digital re-creation of a 2-channel amp and a huge pedalboard.
I've got a couple EQs (used as boosts), 2 drives (each with an x/y state, so technically 4 different drives), a compressor, pitch effect, multidelay (ambient wash), delay, reverb and a chorus. One expression pedal controls the mix of delay, verb, and multidelay between a high and low threshold I have set. The other controls output volume and wah
I have 5 scenes for my "core" tones:
1. Clean-ish w/ short delay / verb
2. Dirtier w/ short delay / verb
3. Clean-ish w/ long delay / verb
4. Dirtier w/ long delay / verb
5. Synth-y fuzz lead
All of that combined with the volume and tone knobs on my guitar is incredibly versatile. I also love that scenes can be configured so that they remember your changes as you switch between them (as long as you don't leave the patch). This is cool because I can set up specific combos of effects on the fly (like in the middle of a show) for different songs on different scenes and then switch between them with one footswitch.
I make additional patches for highly specific effects or tones if I happen to need them for a particular cover (i.e. a specific delay pattern or a synth pad in the background), but in reality, I almost never deviate from my main patch. I find that this has been beneficial for my band's sound. It's made all of our songs (covers included) sound more cohesive and uniquely ours. I'm happy with having "my" tone now. With the GSP, I had way more patches and I hated maintaining them all.
That's another thing: The AxeFX has "Global Blocks". For example: you can dial in your core amp / cab tone in your main preset and then designate those settings as a "Global Block". If you have multiple presets that use the same core amp tone, you can link the amp and cab settings in those patches to the global block you created earlier. If you change the tone in your main patch, those changes are automatically populated to any presets that link to the global block. This can be done with any effect too, not just amp and cab. SUPER useful for maintaining large volumes of patches.