I've got a great DM who's been doing this stuff for years and can run a campaign with his eyes closed, and I just love playing in his amazingly well-developed world.
The only trouble with his campaigns is that he has a great deal of taste for the epic (not level 21+. Just, you know, important) and that makes the adventures take a long time. As is common with DMs, he doesn't dispense XP until the end of the campaign. It's not unusual for us to run through several dozen encounters in one of these campaigns, and we surely have enough XP to level. At the end of the one we're just starting, I expect to hear: "OK guys, you all level up." But I'll know that if he'd let us level mid-campaign we'd have leveled twice or three times.
So when I run my own fledgeling campaign in my nascent world, I level my guys as soon as possible when ever their XP hits the threshold. Of course they can't level in the dungeon, but I may tell them as they exit "After having disarmed the poison-gas barrell trap and leaving the underground facility with your lives and a big sack of loot, you feel more confident about your abilities. You've encountered things you've never seen before, and dealt with them effectively. Also, you've all been paralyzed at least twice."
They may well still be in the middle of the epic (again, not level 21+) adventure I'm running, but they can level and use their new abilities to help them continue in their quest.
If a character has to go more than 14 encounters without leveling, he's probably had enough time to examine all of his character's capabilities, and is ready to level up and play with new abilities.
The only trouble with his campaigns is that he has a great deal of taste for the epic (not level 21+. Just, you know, important) and that makes the adventures take a long time. As is common with DMs, he doesn't dispense XP until the end of the campaign. It's not unusual for us to run through several dozen encounters in one of these campaigns, and we surely have enough XP to level. At the end of the one we're just starting, I expect to hear: "OK guys, you all level up." But I'll know that if he'd let us level mid-campaign we'd have leveled twice or three times.
So when I run my own fledgeling campaign in my nascent world, I level my guys as soon as possible when ever their XP hits the threshold. Of course they can't level in the dungeon, but I may tell them as they exit "After having disarmed the poison-gas barrell trap and leaving the underground facility with your lives and a big sack of loot, you feel more confident about your abilities. You've encountered things you've never seen before, and dealt with them effectively. Also, you've all been paralyzed at least twice."
They may well still be in the middle of the epic (again, not level 21+) adventure I'm running, but they can level and use their new abilities to help them continue in their quest.
If a character has to go more than 14 encounters without leveling, he's probably had enough time to examine all of his character's capabilities, and is ready to level up and play with new abilities.