The best advice I can give is to stick with what you perceive as a good value and works for you. For some liquid supplements don't have the same value as dry compounds and vice versa. It's YOUR tank and YOUR hobby so do it the way YOU want. Each tank is a unique system and may not require certain supplementation methods to achieve satisfactory results. As long as YOU'RE happy with the results that's all that matters.
If you're questioning the use of dry ferts vs. liquid supplements here's a brief list of pros/cons
1. Pro- Dry ferts are less expensive per unit of measurement.
2. Pro- Dry ferts are fairly easy to customize as long as you have the proper measuring tools. I found a Pinch, Smidgeon, and Dash measuring spoon kit (1/8, 1/16, and 1/32 tsp) at a kitchen supply store and it was invaluable for dosing small tanks. A gram scale is even more valuable for accuracy and consistency.
3. Con- Dry ferts are a lot easier to mis-dose which can potentially cause a whole host of problems.
4. Con- Dry ferts and supplementation regimens can be hard to understand and effectively use at first which can cause a lot of problems and frustration.
5. Pro- Liquid supplements are less likely to be overdosed.
6. Pro- Liquid supplements are easier for the less technically inclined to understand or use. "Dose two caps every three days" is pretty darn easy.
7. Pro- Most supplement manufacturers have technical support staff to help people understand and properly use their products.
8. Con- Liquid supplements are a lot more expensive per unit measurement than dry ferts.
Root tabs plus some extra bit of water column supplementation with things like Flourish and Leaf Zone is a perfectly legit means of nourishing your plants.
Again, it's your tank so go with what makes you happy
Oh yeah, clean that damn filter regularly!