Yes I had done it for more than 3L using my plat travel card and got the benefits
It is the best use case scenario and paid all my rents like this and finished my 4L milestone in under 6 months
About 8 months ago,
I loaded MK with Amex cards with:
3% charges,
1% MK CB
1% CB for CC payment using my HDFC Plat DC
Net cost 1%.
Gain from Amex 7%
Net return 6% .. done and dusted plat travel milestone for that year in 5 months
Enjoy..
Need to think about how I do this for the next year in about 3 months time
Note: All numbers are approximate