1. TMH IIT Math and M.L. Khanna IIT Math books make about 20000 problems together. They are important because they are comprehensive.
2. I.S.I. 10+2 Test of Mathematics has about 1500 problems (along with Test Papers)
3. Excursion in Mathematics + Challenges and Thrills in Pre college mathematics together have about 2000 problems.
4. Algebra - Hall and Knight (or better Barnard Child), Complex Numbers from A to Z, (2000 problems)
5. Trigonometry - Loney (about 1000 problems)
6. Coordinate Geometry - Loney (about 1000 problems)
7. Calculus - A combined effort of Apostle, Maron, Piscunov, Tarasov (about 4000 problems)
8. Mathematical Circles, Combinatorics by Brualdi, Selected Problems by yaglom, Problem Solving Strategies by Arthur Engel, IMO compendium, Functional Equation by Venkatchala, Inequalities of Little Mathematical Library and Venkatchala, Number Theory by Burton or Zuckermann should account for the rest 4000-5000 problems.
Note that some problems will need superb intellectual effort, some will ask for tidy computation. So the key is to distribute all kinds of problems in a day. Try about 20 challenging problems per day. Rest 80 should be normal (or subnormal) stuff.
All the best and keep working!