Your picture will be the same if your signal strength is 65 or 99 (its digital) so getting 100 isn't important (and likely not obtainable depending on which scale DISH is using in its software this month. At one time we were getting over 110 on some model receivers).
A GOOD signal is important to help prevent rain fade but if your signal is in the the high 80s and 90s you are fine as far as likely getting as good as signal as you can.