Groups - I have a lot of players, this is just my Faerun campaign. There are 3 Wilderlands PC groups too, but only one is running currently.Yeah, level 5 is definitely a big break point, level 11 much less so though IME. I have one campaign with three active PC groups, PCs can switch between groups, the highest level PC is 10th (thanks to a Comet card from Deck of Many Things) so new PCs come in at 5th level. The current level spreads by group are 6-9, 7-10, and 7-8. Those all work fine in 5e.
1. The Barrowmazers
1. Moxy (Claire) female Tiefling Bard 10, College of Swords
2. Mac (Matt) male Half Elf level 9 Vengeance Paladin 6/Fighter 3
3. Liam (Kermit) male Halfling Arcane Trickster Rogue 8
4. Droghall (Bill) male Kroxiger Totem Barbarian 8
5. Spartigus (Gus) male Human Champion Fighter 8
6. Aya (Judith) female Aasimar Untherite Light Cleric 8 of Shamash
7. Petyr (Jack), male Aasimar Warlock 7 (Celestial)
8. Sir Glendor (Rich) male human Paladin 9 - currently on hiatus
2. The Faerun 7
1. Eamon of the Yellow Rose (Bill) male Human Monk-8 (Kensai)
2. Greeba of Soravia (Jelena) female Half-Orc Barbarian-8 (Berserker)
3. Gorlock the Warlock (Tony) male Half-Elf Warlock-8 (Celestial)
4. Nathia Truthfist (Kimberly) female Goliath Fighter-8 (Champion)
5. Wisteria of Skullspire (Jelly) female Moon Elf Cleric-7 (Grave)
6. Joell Elderberry (Max) male Aasimar Companion of the Noble Heart Paladin-7 (Oath of Conquest)
7. Blurb Birchbark (Phil) male Firbolg Shepherd Druid-7 (Circle of the Shepherd)
3. Norrin's Band:
1. Lord Norrin (Geoff), Knight of Arcata, the Baron D'Ashe, Son of Thorin, Father of Teela D'Ashe Norrinsdottir. Human male Fighter-9 (Champion) PB+3 XP
2. Queale (Keelia) Half-Elf female Horizon Walker Ranger-8 XP
3. Meryem Bloodletter of Reghed (Roxy) Human female Berserker Barbarian-8 XP
4. Goltho 'Bearchaser' (Tim), Goliath male Fighter-6 (Arcane Archer) XP
5. Kevan Blackguard (Jack) Half-Elf male Bard-6 (Lore) XP