Advantage of using different Synthesis Tools?

Iam using three synthesis tools for my code.
-Xilinx XST, Leonardo Spectrum and Synplify pro.
for a any particular code, some show error or warning while the other may synthesize.
The only inference that i got from using multiple synthesis tool is, finding which tool uses minimum hardware.
Can i know any other things(advantages) that i could learn by using multiple synthesis tool.

regard's
Suresh.

Usually I use XST only to get the Area & Timing reports of my FPGA, After that i uses Precision to synthesize the overall design before implementing it on the FPGA. I know that area and timing will differ due to Precision optimization but XST will give me the worst case

Different synthesizers have different strengths and weaknesses. Be sure to read the chapter in your synthesizer user manual that explains how to write HDL that takes advantage of hardware and software optimizations. For ISE, this is the "HDL Coding Techniques" chapter in the "XST User Guide".

by using Synthesis tools one can optimized area time, and also power

Thanks. i think i need to go through the Synthesis user guide.

Is it adequate to master any one synthesis tool or it requires more than one when getting in to the industry? which synthesis tool would be preferred the most?

i am doing a training course in VLSI at present.

regard's...

Added after 29 minutes:

and regarding optimization with respect to area, time and power...

can i know how the code could be optimized with respect to area, time and(or) power...

- are these optimizations achieved based on different coding techniques (if so i guess it would be on the synthesis user manual) 'or' is it achieved by some other process that should be done when creating a 'bit' file?

note: i have checked the output of few simple code using spartan2 kit. but i dint implement any optimization constraints when creating the 'bit' file.

could i get some info on it.

regards...