Yes a fast acting formulation applied in the morning would mean low levels in the evening. Check out this thread:
A very fast acting formulation pulsed once or maybe twice daily may also have minimal negative feedback on your HPTA or let you keep some function.
Creams, troches, and gels would all be testosterone in a base/solvent.
The testosterone ester injectables would be testosterone esterified with a fatty acid to create a time release formula.
So side effects would have to do with the pharmacokinetics (how the testosterone is metabolized and processed by the body). The different routes of administration allow one to control how much your blood levels rise and the peak / trough / duty cycle of the pulses.
Compare plot above (nasal gel) vs plot below (scrotal cream):
A PM dose of the cream applied on skin is going to be with you for a while and into the evening. Nasal gel would be in and out in a few hours.