I like agile approach, because classics waterfall with yearly plan is just somewhere other planet. But weekly demo is too fast, this is near impossible to impl

I like agile approach, because classics waterfall with yearly plan is just somewhere other planet. But weekly demo is too fast, this is near impossible to implement something really techie. I think, really adequate timing, should be "tick-tock" style, mean period of making feature, then period to lower tech debt. To be strict, I think good enough 2 weeks to make demo, then 2-4 weeks to eliminate debt (may be prolonged).