I think multi-tabling is worth it, but only once you're comfortable with your decision-making on a single table.
When I first started, I found that adding too many tables caused me to rush decisions and miss important information about my opponents. It was much better to gradually increase the number of tables as I became more confident.
These days, I prefer playing 2–4 tables at once. It keeps me engaged and increases the number of hands I play without feeling overwhelmed. I'd rather play fewer tables well than try to manage 8+ tables and make costly mistakes.
Quality of play is always more important than quantity. If adding another table starts hurting your win rate, it's probably better to scale back.
How many tables does everyone here usually play at once?