Your Forum name was wisely chosen :)
It depends on the size of the venue and the scope of the sound system.
Example of a Band.. Dr Fun and the Nightcrawlers. up to 10 piece R&B band. drums, bass, keys, 2 guitars, lead vox with Harp, 3 piece horn section. Not much money to work with , most equipment very well worn and banged up.
I was their sound guy for 10 years. We had a 24 channel soundcraft with 4 Aux and 2 Effects loops. It also had 4 bus submix. All XLR patches.
Heres how the output list looked:
Sub mix 1/2 to Mains to FOH power amp and speakers system
Sub mix 3/4 to powered sub Bass bins and a drum monitor. ( we used a old Peavey bass amp ) Only bass and kick.
Aux 1 vocals 2 wedges singer and guitars
Aux 2 Horn section 1 or2 wedges depending on stage.
Aux 3 Keyboard 1 wedge
Aux 4 Side fill speakers on stands. This was a mix of everything but drums and bass. Some venues were so small this was all we had room for and it worked just fine if they kept their levels down.
OK then they would do a festival stage which we would have probably up to 12 monitor mixes to work with which almost made things worse because now your not sharing and you get too picky :) Those systems are beond the scope of a weekend band. That involves an seperate mixer aptly called the Monitor mixer. Those are specially designed boards with up to 24 matrixes. The stage mikes and DI's all pass throught his board first and are iso connected to the snake to carry on to FOH.
These days large bands are best off with in ears monitors.
Each floor monitor system is a whole PA in itself with a price tag of easily $600 per speaker. That money could be put towards personal monitors,,, see the other thread here about that topic.
Myself I like side fills with In ears as the best of both worlds. Last band I was in we had no stage speakers at all.