Heavy usage is part of it, but I also think that whether you have "enough" in Chase's eyes is another factor. If you're running through 70k per year and have 30k in overall limits with them, they may give you an auto CLI. However if you have 100k in total limits and still spend 70k a year, they may look at it and say "your limits are high enough for your current level of spending. If your spending goes up even more, then we'll have another look at your limits then".
EX 798, EQ 789, TU 784
American Express Platinum (NPSL) || Bank of America Privileges with Travel Rewards Visa Signature - $23,200 CL
Barclays American Airlines Aviator Red World Elite Mastercard - $20,000 CL || Chase IHG Rewards World Mastercard - $25,000 CL
Chase Sapphire Preferred Visa Signature - $12,700 CL || Chase United MileagePlus Club World Elite MasterCard - $26,500 CL
Citibank Hilton Reserve Visa Signature - $20,000 CL || J.P. Morgan Ritz Carlton Visa Signature - $23,500 CL
