When the slides are too dense then either the film requires a lesser EI or the time in the first developer needs to be increased. If the slides are too thin then the film requires a greater EI or the time in the first defveloper needs to be shorter. Film for reversal processing is usually not shot at box speed. Remember this is reversal processing and things work sort of backwards. The exact EI varies from film to film. If you are not following a recommended procedure for a specific film then you will have to bracket at first to determine what EI is best.
A 1 min exposure to a 250W photoflood lamp should be sufficient for re-exporure. When using SS reels the film can be left on the reel. Just hold it approximately 2 feet from the light and move the reel so the light can reach all portions of the film. A re-exposure is not needed if you use a fogging developer as given below.
The second developer or a fogging developer goes to completion and so over development is normally not a problem. A simple re-useable bath containing 100 g of sodium carbonate and 2 g of thiourea per liter can be used instead of a conventional developer. This bath can be saved and reused several times. A commercial sulfur based toner can also be used. Both baths yield pleasing sepia colored slides. The film should not be fixed again after either of these baths but should be washed thoroughly. The T-Max films do not give good results with with thiourea or sulfide developers.